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Links to answers:
- Why do males have shorter wings?
- How do you sex cockroaches?
- Desperately seeking Blaberus giganteus?
- Do cockroaches sleep?
- Are cockroaches resistant to radiation?
- Why do cockroaches die on their backs?
- Do cockroaches bite?
- Is there a non-toxic way to kill cockroaches?
- American cockroach lifespan?
- Blaberus discoidalis lifespan?
- Lobsters called "roaches of the sea"?
- Are cockroaches really clean?
- Can cockroaches live without their head?
- Do cockroaches make sounds?
- Green cockroach?
- 20 lb cockroach?
- Live cockroach in beer bottle?
- Do cockroaches fly?
- Do cockroaches respond to light?
- Could cockroach eggs hatch from an infected tongue?
- How do cockroaches breathe?
- Is the cockroach's brain spread around its body?
- What are cockroaches good for?
- Albino cockroaches?
- Do cockroaches hibernate?
- Why GERMAN cockroach?
- Cockroach survival in cold climates?
- What do cockroaches eat?
- Do cockroach eggs survive being stepped on?
- Are cockroaches really members of the Carp (fish) Family?
- Color of cockroach blood?
- Do cockroaches like air conditioning?
- Are single cockroach sightings scouts?
- How big is a cockroach baby?
- Trouble maintaining cockroaches sent to Albany?
- Do cockroaches have a support system?
- Is the cockroach exoskeleton an improvement over the worm
hydrostatic skeleton?
- Could cockroaches develop albino mutants in the wild?
Are they rare?
- How do Cockroaches Digest and what organs do they use to
do so?
- Do cockroaches glow under black light? Are they
flourescent?
- Can cockroaches predict earthquakes?
- What would cockroach vision be like?
- How can I tell if a cockroach is breathing?
- What is the reason for cockroach swarming?
- Do male and female cockroaches of the same size have the
same blood volume?
- Where did the cockroach get its name?
- What is the cockroach reproductive cycle?
Q47: Alexandra Manou asks:
What is the cockroach reproduction cycle? ... Was told by pesticide company that
it is 40days, including winter. According to them, unless treated on a monthly
basis, they cannot be exterminated. Is this true or an excuse for frequent
visits?
A: Alexandra,
The reproductive cycle like the life cycle depends on the temperature. It is
maximum for most pest species at 30ºC which is about 86ºF. At that temperature
an egg case is produced by _Blattella germanica_ adults in about 6 days but it
is held by the female for 18 days before they hatch. The other common pest
species, _Periplaneta americana_, deposits an egg case every 3 days at 30ºC and
each egg case will hatch in about 30 days. Perhaps that is the magic number 30
that corresponds to the lunar monthly cycle that your exterminator has suggested
is critical for visits.
The rates of egg production and development are temperature sensitive so at
25ºC all the above times are approximately doubled, slowed down by the reduced
temperature. Another 5ºC reduction again doubles the times and thus the German
cockroach egg laying and hatching cycle would be quadrupled from 24 days to 96
days.
Most homes are cooler in the winter than the summer so roaches are probably
growing and reproducing slower in the winter than the summer. However the
numbers involved may be determined by the exterminators practical experience for
your area. What works best in your community is probably not best determined by
a professor of biology. For instance, the outdoor cockroach refuges that provide
the reservoir of pests that would enter your home may be the determinant. In
cities, the sewer system may be the major reservoir of cockroaches and it is the
temperature there that possibly drives the infestation rate. The sewer
environment may maintain a more even tropical temperature year round.
Q46: Thomas Coxey asks:
Where did the cockroach get its name?
A: Thomas,
Pest cockroaches have lived with people of many cultures perhaps before language
developed. Here is a link to the common names given to cockroaches in different
cultures:
http://open-dictionary.com/Cockroach
Some common names have some suggestive associations. (1) Water Bug. (2) The
German cockroach, Polish cockroach, Russian cockroach, Crotton bug all refer to
the same species Blattella germanica because one community wanted to name
it after something they despised. (3) Some dominant societies have named their
local pest cockroach after their oppressed native population. This practice is a
sad reflection of how far prejudice has driven our common language.
Our common name 'cockroach' shares sounds with Dutch 'kakkerlak' and Spanish
'cucaracha' and the Spanish dance the cucaracha suggests the vigorous stamping
of a homeowner on the pests. The origins of the names are entwined in early
cultural history and only careful etymological and sociological study might
discover the origins of our word 'cockroach'. I am not aware that such research
has been successful in this case.
Q45: Frank Melchior asks:
I have a question. ... Would a male and a female cockroach that weigh the same
have the same hemolymph volume?
A: Frank,
Larval males and females of the same size have the same hemolymph volume. Last
instar females are bigger than last instar males, anticipating the larger
abdominal format of the females and tend to have more hemolymph.
Adult females are generally more robust than females particularly in the
abdomen where the ovaries of the female take up substantially more volume than
the adult male gonads. In addition the fat body of the adult female is much more
developed due to its involvement in vitellogenin synthesis in support of egg
development. Coincident with this greater abdominal tissue development there is
more hemolymph in the reproductive adult female.
Finding an adult female the same weight as an adult male might be difficult.
The largest adult males and the smallest females might be the same weight and
perhaps they might have the same blood volume but I doubt it. The females more
extensive abdominal tissues are all laminar and would require more volume of
blood to suspend them. I hypothesize that if you measure male and female blood
volumes the adult females would have a larger blood volume when regressed
against weight due to their greater tissue surface needs.
Q44: Katherine McGlothlin asks:
What was the reason for this cockroach behavior? On Sept.29 around 9:00 pm in my
front yard ... I observed a large number of cockroaches (maybe 100-200) pouring
out of a manhole. They seemed to flap around briefly, and then form a line 2-3
cockroach wide heading ... towards a large tree. Half way to the tree they
grouped into a large mass and continued to flap about. It almost seemed to be a
mating frenzy. This sight, ... was observed by the light of a full moon, was ...
interesting and also creepy.
A: Katherine,
I am not particularly a behavioral expert but I have seen such a frenzy in the
lab on a smaller scale when I added a bunch of mature adult males to a bowl of
virgin adult females who were all ready to mate.
What you observed in the wild does sound like a mating frenzy. The population
pressure in the utility/sewer was probably pretty high. One or more females were
probably sending out sex pheromone signaling that they were ready to mate and
they were being mobbed by males who were ready to mate. The flapping of wings is
the males' signal to the female that they are ready and the males would pursue
the females and occasionally bunch together around what they sense was the
source of the pheromone. The females would respond by palpating the abdomen of
the male she chose to have sex with and if she was really ready she would
copulate with the most 'attractive' male.
I do not know how common the mobbing phenomenon is but I expect it often happens
down in the sewer as long as the population pressure is not high.
I also would assume that it was only adult cockroaches that participated. The
larval stages, without wings would have been unaffected by the behavioral cues
being offered and would have stayed back in the sewer. This behavior might have
the purpose of getting the adults in a crowded population to disperse before
they mate and produce eggs. A close relative, the termite, exhibits this adult
mating flight swarming quite frequently. It is interesting that you may have
stumbled on observing one of the traits that link the two groups (termites and
cockroaches) from a behavioral point of view.
Q43: Cressida Mahung asks:
How can I tell if a cockroach is breathing? How do I measure the breathing
rate? I would like to do project on this for my science fair, but I am stuck!
A: Cressida,
The cockroach's breathing rate, like that of most insects, is controlled by
carbon dioxide, not oxygen. In order to conserve water, the average insect
closes its spiracles which are the openings of the insect tracheal system that
supplies oxygen to all tissues and removes the carbon dioxide. When the carbon
dioxide in the animals system rises to a critical level, the spiracles open and
then CO2 leaves the system and oxygen enters. In most small insects
this opening and closing of the spiracles (breathing?) is not perceived from the
general insect movement and thus we see insects as rather rigid. We see no
obvious breathing.
If you however look at breathing as the uptake of oxygen from the available
volume of air you could measure this disappearance of oxygen as volume of gas. I
have done this in a student laboratory using an apparatus similar to the diagram
below, a small vial with a stopper in its end through which a breathing tube is
inserted:
____________
|___________|_|=========
If you put an animal in the vial above and keep the vial in a constant
temperature water bath then the water will enter into the small tube that goes
through the stopper and the water will continue to be drawn in through the small
tube as oxygen is used up, somewhat like the mercury in a thermometer. CO2
dissolves in the water and is thus removed as it is expired by the insect and
thus the volume declines as oxygen in the air is used up by the respiring
insects. By measuring the position of the water in the tube you can measure the
usage of oxygen. This is the long accepted method of measuring respiration of
such small animals.
You could also restrain the insect under a microscope so that you could watch
the spiracles and watch them open and close. However, a restrained insect often
struggles and its use of oxygen will go up abnormally. Some minimal restraint
might be designed such as gluing the pronotum to a wand and giving the insect a
small light ball to "walk" on. The wand can be maneuvered to allow the abdominal
spiracles to be observed by a dissecting microscope, allowing the spiracular
opening rate to be counted.
Q42: Joe Rowell asks:
I am a illustrator going to Savannah College of Art and Design and I am trying
to illustrate a image from a roaches point of view. What would that look like?
A: Joe,
You would be looking out of a crack at the world during the early morning or
during the day in a half stupor because you would be hiding there sleepy or
asleep from 2AM to 10PM. At 10 PM when the human household turns off the lights
you would come to life and be looking at the world from weird angles since you
would be scuttling on the floor or viewing the room in dim light from standing
on the wall or the ceiling.
Q41: Alejandro from the Phillipines asks:
... I have observed that cockroaches in my house get "wild" before any
earthquake occurs. They start running and getting out from their niches. ... I
have the impression that cockroaches can "feel" some of the very early
vibrations of an earthquake, small or big, and can be a very good help to give
"early warnings" of earthquakes. Can you confirm this?
A: Alejandro,
If you have done a careful experiment to demonstrate the phenomenon you should
publish it. There have been newspaper articles professing to demonstrate that
point (perhaps 20 years old) but I have never seen confirmation of earthquake
prediction by cockroaches in the scientific journal literature. The type of
proof that would be needed is a type of automated or regular observational
record of the cockroaches and the demonstration of how that record changes and
predicts future seismic activity. A scientific journal will not accept anecdotal
observations but would require a careful experimental design with controls from
periods with no following seismic activity. Reliability would be another issue.
Do the cockroaches predict every earthquake? Are there times they produce a
false positive, i.e. their activity predicts a quake that does not happen?
A better approach would be to build a small chamber that would act as an
activity meter which would automatically record the cockroach activity. There
are several designs for a cockroach activity meter. One that might be useful is
a small light plastic pie plate with lid. It would sit on a metal base that
would conduct electricity. The plate would sit on a pin at its center that keeps
the pie plate off the metal base except at one point on its rim. A large
cockroach such as Periplaneta during its normal activity cycle would make
the pie plate rotate on the metal plate as it walks around the plate. A wire at
one or more places on the rim would make a circuit and that circuit closure
could be recorded with its time of occurrence. This activity rhythm (because
cockroaches are normally active for 4 hours after lights go out in the evening)
recording gives one a record of the normal activity something like the
following:
||| |||||||||| |||||||||
|__________________________________________|_______________________________________|
0 12 24 12 24
Midnight Noon Midnight Noon Midnight
Then your seismic event might look like:
||| || || | X |||||||||| |||||||||
|__________________________________________|_______________________________________|
0 12 24 12 24
... which predicts a seismic event at X, about 13:00 or 1PM.
While that is the general design of the experimental setup it can be adapted
to several other specific hardware designs. For instance the analog design
described above could be changed to a sold state and digital design by using a
digital camera or camcorder to take a digital image of the cockroach in its dish
which would record if it has moved since the last picture. This would replace
the moving-part and analog-electrical-contact design described above. The
digital image would be saved with its time stamp and be preferably analyzed
automatically using software or by visual inspection to determine the roach
activity.
I understand that these approaches might be beyond your technical
capabilities but that is why we have research labs at universities and
commercial labs that do this type of sometimes expensive basic and applied
research. Such designs, once proven in the lab, possibly could be commercialized
and be able to be packaged with computer software as a seismic prediction device
which could be located in a local prediction center or police station where a
perhaps automated warning could be broadcast to the public.
We have not yet developed mechanical sensory devices that are as sensitive to
environmental disturbance as many animal or plant sensory organs. This area of
research has been dubbed 'biosensors' and grants are available to pursue such
questions. Ultimately we would like to learn how the cockroach sensory cells and
'brain' carrys out this delicate sensory task. Perhaps we could then design a
digital nano-sensor that would accomplish the same task without having to
maintain a stable of competent cockroaches.
Q40: Marlene asks:
A former science teacher said that cockroaches glow under black light. Are they
flourescent?
A: Marlene,
I have never seen a cockroach glow under black light however other pests in more
tropical or desert regions, the scorpions, do glow fluorescently.
Scorpions are well known for this behavior. Their generally soft cuticle has
fluorescent compounds. There is a famous picture on the cover of Science of a
fluorescent scorpion. I once took a walk in the evening desert outside
Albuquerque NM with a portable black light. The cresote bushes, after dark,
illuminated with black light became like Xmas treess illuminated with scorpions
which were foraging for prey on all the twigs and branches of each bush. It was
a powerful demonstration of how physically active they become at night and just
how many scorpions are out there.
Perhaps some cockroach species would show some flourescence but I have never
seen it nor heard of it from any other experts.
Link to abstract on this topic
Q39: BEH301 asks:
How do Cockroaches Digest and what organs do they use to do so?
A: BEH301,
You can look at the diagram at URL:
http://www.bio.umass.edu/biology/kunkel/rolleston/plate_viii.html ... This
is an illustration by GEORGE ROLLESTON published in 1870.
Cockroaches shred food with their mouthparts and then swallow it using their
salivary glands (e) and salivary reservoir (f) to moisten their food before it
enters their crop (d). Their gizzard or proventriculus (g) grinds the moist food
further and adds it to the stomach (i) into which digestive enzymes are poured
from the gastric caeca (h), after which it flows into the intestines (l) which
is shown separated from the tubular stomach by a short segment of the
peritrophic membrane (k) which is a chitin sac woven by the microvilli of the
stomach to contain the bolus of food which passes through the GI track. The hind
intestine (lower-l) removes water from the digestate and then the rectum (m)
compacts the remains into a roach scat. The digested food is relieved of its
nutritive materials by the walls of the stomach and intestines.
Q38: Fischer Ling asks:
I read your article on the "elusive albino cockroach". Just hope that you can
provide me with more insight on the following (3) questions:
Q38.1: Is it scientifically possible for a albino cockroach to mutate in the
wild naturally? Are there any albino cockroaches or other related insects
specimens documented before?
A1: Such mutants are possible but the hardness of the cockroach cuticle
depends upon the tanning process which cross-links its cuticle with a process
that creates a mahogany-like color. Thus an albino cockroach (or other naked
insect) would have weakened cuticle which would make it very vulnerable to
attack.
In insects clothed in colored hairs or scales the color of the scales can become
white due to the storage of white substance in the scales. In this sense the
underwing moth, Catocal relicta, has an albino morph which is able to
hide on birch bark trees based on its ability to hide on the cryptic bark
surface, URL:
http://www.bio.umass.edu/biology/kunkel/catocala.html
Albino examples such as the one above are relatively common in insects. They
were observed by midieval monks who manually transcribed the bible and included
the albino genetic "sports" as decorations in the margins of illuminated
manuscripts.
Q38.2: I have personally seen American cockroaches ... that are not
entirely brown. I have seen one (full grown adult) with partially white wings
and my friend claimed to have collected one with white eyes. Are these rare
finds?
A2: If injured while molting a cockroach may not fully tan its wings. White
eyed Periplaneta cultures are available in some labs but I am not aware
of how frequent the gene is in the wild and whether any of them are based on
distinct genes. There are dozens of genes for abnormal colored eyes in
Blattella germanica, not all are white. It would be interesting to cross the
available white eye Periplaneta cultures to see if they complement each
other (i.e. are from distinct mutant genes). These albino mutant eyes are
mutations of the eye pigments which does not involve the cuticle and thus there
are not the limitations to the structural properties of the cuticle as is with
the surface integument.
Q38.3: I saw a documentary ... reputable organization who claims that a
cockroach has two "brains" one in front and one behind. That is why a cockroach
... continues to function as per normal (except feeding) when its head is cut
off. Is this true?
A3: That is true. The reproductive behavior is somewhat driven by its
terminal abdominal ganglion, the VI abdominal ganglion, which is quite large.
The preying mantid is in the same insect Order, Dictyoptera, and it is famous
for the males prowess in completing sexual behavior after the female has bitten
off the male's head. In this case the brain (in the head) is thought of
inhibiting the reproductive behavior and when bitten off the reproductive
behavior, released from inhibition and programmed into the VI ganglion, takes
over.
The cockroach VI ganglion is responsible for coordinating the reknowned escape
reflex of the cockroach. Delicate hairs on the cockroach hind end detect air
rushing in front of a predator. The sensory hairs transmit heir signals to the
VI ganglion, it interprets the signals as an attack (or not) and accordingly
sends a rapid message to the thoracic legs to start running. This escape reflex
does not require the coordination by the (anterior) brain in the cockroach head.
Q37: Kunal Patel writes:
(Does) the presence of an exoskeleton (in cockroaches) increase the efficiency
of locomotion in comparison with the hydrostatic skeleton of worms?
A: Kunal,
I assume you are referring to annelid and polychaete worms and not the larvae of
insects (e.g. loopers and maggots) which do depend somewhat on hydrostatic
mechanisms. Given that spiders, like worms, have a partial hydrostatic skeleton
I am not sure that there is any difference in efficiency unless you say that the
success of insects vs spiders shows that the insect design is more successful. I
would say that the variety of motion shown by insects is an indication of the
benefits of the opposing-muscle approach to design. Insects have established
several mechanisms of flight while spiders have only been able to do it by
parachuting. Perhaps this is an indication of the limits of a hydrostatic
skeleton. I am not sure that it says anything about the efficiency of comparable
motion in a biophysical sense. When a hydraulic system is more efficient, the
insect uses it. The spider is limited to using blood pressure to extend limbs,
perhaps because they have not developed an easy local sclerotization of
structures by which to create the fulcrum and levers for extensor muscles to
work. Again this does not speak to whether the blood pressure extension is more
or less efficient. I would think that controlling localized pressure differences
allowing dexterious extension of one limb but retraction of another would seem
to be less efficient. The tubular worms on the other hand do not in general have
the problem of multiple appendages needing separate control; however they can
extend different segments of their body by resisting extension in select regions
by using their retractor muscles in those regions.
Q36: Samantha writes:
I am doing a report on cockroaches and was wondering what are cockroach's
support system(s)?
A: Samantha,
This is clearly an assignment from someone who knows the type of answer they
want. I am not sure what the questioner wants.
I imagine that the majority of the approximate 3000 cockroach species are
largely on their own in the environment. Their support is based on their
membership and place in the food web. They are omnivores and thus eat almost
any organic matter that does not fight back. They are eaten by many small
lizards, amphibians, mammals, and birds. Domesticated cockroaches (about 10
species throughout the world) have found it easy to live with humans and get
their food, water and shelter from the human shelters in which they live. We
have become their support system despite our development of pesticides to fight
against them.
Q35: Diane Wilson writes:
I am a graduate students at UAlbany (NY). Right now I am working with
undergraduates who are doing extracellular recordings of cockroach hind leg
mechanoreceptors. We are having a hard time keeping our roaches alive and have
resorted to trying to catch them around the building with limited success. Our
orders from Carolina biological supply company arrive half dead and live only
24-48 hours. I was hoping you have some suggestions as to a good source,
trapping tactics and stratigies for maintenance.
A: Diane,
Cockroaches should be kept and reared at a temperature close to 30°C. If you
allow them to chill they will die of cold shock. That is most likely the reason
for your roach deaths after shipments made during the winter in your latitude.
25°C-30°C is the recommended growing temperature for Periplaneta. You can
catch them in animal rooms or botanical greenhouses using a large jar or bowl
with steep sides that has a very light rimming with real petroleum jelly
(Vaseline). Bait the trap with banana or potatoes and carrots and place it in a
warm moist area overnight. There is no excuse for failure!
Q32: M.I.A. writes:
My roommate believes that cockroaches don't like air conditioning. ... we live
in Hawaii, and air conditioning makes the temperature around us liveable, plus
it can cause droplets of water to form, .... What is your opinion?
A: M.I.A.,
Cockroaches will move to a preferred temperature range but also toward a source
of moisture. They prefer a temperature between 25-30°C. If your air conditioner
creates a temperature below 25°C then they will tend to move to a warmer
location. 25°C is (25x9/5 +37) = 82°F so your air conditioner is probably set to
cool below 80°F and tend to repel them. If you turn your AC off occasionally,
the water the AC has dripped outside may have attracted cockroaches and provide
a local source of cockroaches to move into your temprarily unconditioned space.
It is not a simple question.
Q33: M.I.A. writes:
Also, My roommate says that, if you have previously never seen any cockroaches
in your romm, but one day you see a huge one, then it is a scout, and is not
really indicative of the size or amount of cockroaches which might be living
within your walls. Is this true?
A: M.I.A.,
The large roaches are more likely to travel than a small roach. They do not have
a social network that would include scouts. Bigger stride and wings allow adult
cockroaches to travel further. Some male cockroaches can even gain altitude when
they fly, most only use their wings to glide.
Q34: M.I.A. writes:
Also, how big is a cockroach baby or nymph? Occasionally I have seen very tiny
(about the size of two fruit flys) beetle creatures in our apartment. (Are these
baby cockroaches?)
A: M.I.A.,
I can not identify things I can not see. The size you mention is about the size
of a first instar cockroach. You can see an example of a recently hatched first
instar American cockroach on a dime at URL:
http://www.bio.umass.edu/biology/kunkel/jpegs/pam_fam1.jpg
... a German cockroach newly hatched larva is half that size and black. Other
beetle like creatures (such as carpet beetles and flower beetles) can invade a
house also.
Q31: Pam Pollister writes:
What color is the blood of a cockroach?
A: Pam,
The long answer:
Cockroach blood is not red because they do not use hemoglobin to carry oxygen.
In fact their bloodstream is not used to carry oxygen either. They use a system
of pipes called tracheae to bring the oxygen and remove carbon dioxide from
their tissues.
As a result other factors determine the blood color. Male cockroaches have
relatively colorless blood. Larval females have colorless blood. Only adult
females which are producing eggs have a slightly orange blood because of the
protein vitellogenin which is made in the cockroach liver (its fat body) and
transported through the blood to the ovary. This protein like chicken yolk is
orange because it carries a carotenoid, which is a vitamin A like molecule
needed by embryos to develop normally.
The short answer:
Cockroach female adult blood is occasionally orange. All other cockroach blood
is colorless.
Q30: Clifford writes:
Are cockroaches really members of the Carp (fish) Family?
A: Clifford,
A cockroach and a carp are in two different Phyla. The cockroach is an Arthropod
and the carp is a Vertebrate. The closest traditional link is that they are both
in the Animal Kingdom. Some have been confused perhaps by the close spelling of
the Stick Insect's scientific name, Carausius morosus, URL:
http://www.uni-bielefeld.de/biologie/Kybernetik/research/morphology.html
and the gold fish's scientific name, Carasius auratus, URL:
http://habitatnews.nus.edu.sg/guidebooks/freshfish/text/210.htm
The similar spelling of the Genera of the stick insect (Carausius) which
is sometimes grouped with the cockroach and the goldfish (Carasius) which
is related to the carp could have confused some into thinking a carp and
cockroach were closely related. However your confusion is more likely based on
the carp having another common name, the roach, BUT not the cock-roach.
Q29: Leigh writes:
Me and my friends wanna know if the myth is true or its just an urban legend
that cockroachs' eggs spread when u squish them with your shoe and you can
spread them around where you walk?
A: Leigh,
You and you friends are possibly responding to the urban paranoia about
contracting and spreading cockroaches in ones work and home environments. It
seems that they are everywhere and if your apartment or home gets infested one
can begin to speculate on how those buggers got into your 'space'. You have
correctly identified it as an urban legend.
It is highly unlikely that a cockroach egg case (ootheca) would survive a
classic smooth leather soled shoe. But who wears smooth soled shoes these days?
If an ootheca was lucky enough to lodge itself into the honeycomb of a sport
shoe tread and the person took off the shoe in disgust and threw it in the
corner, I could imagine the eggs surviving and the brutal attempt to end their
young lives might have failed.
However the ootheca and contained eggs are huge and mechanically fairly fragile.
Any good mashing should kill them all.
I am sorry if I have started another urban legend about the paranoia of passing
cockroaches with improper footgear!
I am not recommending going back to smooth soled shoes but I would recommend
looking at the size of the waffle holes in your sport/walking/running shoes to
see how they compare to the size of an ootheca which is about the size of a pea.
Q28: Lynn Gant writes:
What do cockroaches eat?
A: Lynn,
Cockroaches are omnivores, like us. For the most part they will eat anything
organic. Mostly they eat dead or immobile things. As indicated elesewhere in the
FAQ, they rarely bite a human but might nibble on a sore in the middle of the
night when an animal is sleeping.
They will eat the glue off the back of postage stamps and the glue bindings off
the backs of books, traditional glue being derived from animal protein.
Q27: Bill writes:
Do cockroaches live in cold climates. Or put it another way. "Can cockroaches
live in Canada?" withstanding long cold winters? Please settle an argument! I
have been told cockroaches can not live in Edmonton Alberta. Is this True? or
False?
A: Bill,
Domestic pests certainly can live in houses in Canada but not outside, the way
they do in Florida or the Gulf coast.
There are numerous wild cockroach species which can live in Canada as they do in
the northern USA. The adults or larvae over-winter in the ground litter and
effectively hibernate. There are some of these species that I have reared in the
lab which queue up at a particular larval stage and refuse to proceed with their
development toward the adult stage until you give them an artificial winter.
Q26: Felicity West writes:
I would like to know why this is called a German cockroach please? There are
apparently no cockroaches in Germany so where does the name originate from?
A: Felicity,
The chief biologist at the Munich TierPark (zoo) said they had no German
cockroaches in their zoo and gave me three tropical species that they knew were
living in various environments they maintained in the park. But I knew better. I
went to the reptile house which is kept hot and humid and saw loads of
Blattella germanica (Linnaeus,1767) in the space of a half hour, and during
the day at that! B. germanica, the German cockroach, probably entered
Europe with Marco Polo or along early trade routes. Southeast Asia is its most
likely origin. There are several sibling species that are very close to B.
germanica; some even cross breed with it. Its relatives are common around
pig stys in the outer islands of Hong Kong. Live pigs were often kept on
exploration ships during long trips. It became associated with man and traveled
around the world. It was formally named by Linnaeus and probably was around in
Germany for quite a while before the name was applied. In Germany it is
sometimes called "Die russische Schabe", The Russian Roach. In Russia it is
called the Polish Roach. In America it was called the Crotton Bug because it
came to NY about the time the Crotton Aqueduct was built which was pilloried in
the papers because it took so much land by eminent domain.
The American Cockroach, Periplaneta americana (Linnaeus 1758) likewise is
a misnomer since it probably originated in North Africa before becoming a world
traveler. It most likely reached the Americas during the early slave trade.
There are thousands of species of cockroach and only about 10 have become
cosmopolitan pests of man. Most of the others do not even have a common name.
Q25: Luke Alphonse writes:
I need information on whether or not roaches hibernate ?
A: Luke,
The wild cockroaches in the northern USA do hibernate. They go into a suspended
state of development in late fall and then they must go through a dormancy phase
in the winter before they will resume development in the spring. If you keep
them in a warm environment during the winter they will not develop any further
and remain in a suspended state for more than a year. This phenomenon has not
been published on as far as I know. The species I know this about through my
unpublished research are Parcoblatta pensylvanicus and Parcoblatta
virginica. It would be interesting to know if these species go through
this hibernation in the southern reaches of their range where a hard winter is
not experienced.
Q24: Mkrs0042 writes:
My daughter told me she was at a friends house and they had WHITE cockroaches!!!
UGH. I have never heard of them. Is there a such creature?
A: Mkrs...,
That is a common observation; look at URL:
http://www.bio.umass.edu/biology/kunkel/bgmolt.html
Q23: Nick writes:
I am deathly afraid of cockroaches and it may soothe my fear a little if I knew
they had a purpose. What are cockroaches good for?
A: Nick,
Fear of domestic cockroach pests is perhaps warranted because they have been
associated with the development of childhood asthma and thus it is better not to
have them in your home environment.
Cockroaches as a group are part of the worldwide food web. They are omnivore
scavengers which clean up our environment and help recycle the organic litter
that would accumulate if it were not decomposed by organisms which include
cockroaches. Furthermore they serve as food for small mammals, birds,
amphibians and lizards. There are over 3000 species of cockroaches and only 10
species are on the World Health Organization list of human pests. The other
3000 species are welcome members of the biodiversity on this planet.
Q22: Joanna writes:
Is the cockroach's brain spread around its body?
A: Joanna,
Insects as a group are said to think in their periphery. This is because many
of their innate behaviors are hardwired in peripheral ganglions more so than
vertebrates. For instance flying behavior is controlled in the thoracic
ganglia and some reproductive behavior such as copulation is controlled in the
last abdominal ganglion. Whenever sexual behavior or flying behavior has to be
coordinated with the visual system the behavior includes what you might call the
brain (head ganglion). The standard cockroach escape mechanism involves the
tail (cerci) sensory signals that impinge on the terminal abdominal ganglion
(A6) and giant fibers that communicate an escape signal from A6 to the 3
thoracic ganglia (T1-T3) which control the legs in running behavior. So people
might say that the cockroach's brain is spread around the body in abdominal
ganglia A1-A6 and thoracic ganglia T1-T3 and head ganglia (brain, frontal and
suboesophageal ganglion).
Q21: Ajay writes:
Could You please let me know how do cockroaches breath?
A: Ajay,
Cockroaches, like all insects, breathe through a system of tubes called
tracheae, a word similar to the name of the tube leading to our lungs. The
tracheae of insects are attached to the spiracles which are small valved
openings on the side of each body segment, excluding the head. Thus the
cockroach can breathe without its head! The valves open when the CO2
level in the insect rises to an unacceptable level; then the CO2
diffuses out of the tracheae to the outside and fresh oxygen diffuses in. The
tracheal system brings the air directly to cells because they branch continually
like a tree until their finest divisions tracheoles are associated with each
cell allowing gaseous oxygen to disolve in the cytoplasm lying across the fine
cuticle lining of the tracheole. CO2 diffuses out of the cell into
the tracheole.
Most insects do not have muscular lungs and thus do not actively breathe in
the vertebrate lung manner. However in some very large insects the diffusion
process may not be sufficient to provide oxygen at the necessary rate and body
musculature may contract rhythmically to forceably move air out and in the
spiracles and one can actually call this breathing. This might be associated
with such activities as the energetic flight of the migratory locust.
Q20: Anthony writes:
... a story (is) reputed to have aired on CNN about a woman, who while licking
an envelope, got a paper cut from the flap on her tongue and was exposed to a
cockroach egg which incubated inside her tongue. The woman later had the alive
roach removed by a doctor. Is this possible?
A: Anthony,
This item is utter trash. The cockroach egg is huge. Most eggs are 2 mm long and
are closely packed side by side and 2 by 2 like franks in a dozen package. They
do not survive outside of the oothecae or egg case, which contains 12-40 of the
eggs, and I can not imagine them being associated with the lickable surface of
an envelope in any way such that they were transferred into a paper cut tongue.
You just have to sit back and laugh at the gullible nature of the CNN
producer/director who did not have enough biology in his education to know when
he/she was out of her depth and needed to consult with someone who knew better.
The producer/director of that program should be fired for promoting
misinformation. I almost doubt that it ever aired.
Thanks for playing the skeptic!
Q19: Rachele Besley writes:
I am a ... student from New Zealand doing a study on Cockroaches and was
wondering whether you could tell me something on their response to light,
whether they are attracted to it or not and whether it affects their behaviour.
A: Rachele,
I did a quick search on cockroach circadian behavior and found the following
references ... of papers.
I understand that you ... may not be aware of some of the technical language in
these (titles) but perhaps some of it will be useful. Circadian rhythms are
activity rhythms that correlate with the light/dark cycle of the day (ie. the
normal 24 hour day/night light rhythm). When organisms are put into constant
dark they continue to behave as if the normal light/dark cycle was still there;
that is they anticipate being awake when they normally would, during the 4 hours
after lights go off at night. This internal clock can be reset by an
artificially imposed lights off that a researcher imposes in a research arena.
This demonstrates that the cockroaches respond to light and can reset their
internal clock to a new rhythm as they should be able to since dusk changes its
time of onset gradually during the year.
You can do a search of the scientific literature using other key words at the
following URL:
http://www.ncbi.nlm.nih.gov/entrez/
For example try searching for the keywords: cockroach vision
This is one of the free ways of searching the scientific literature that you can
do yourself. When you find things you do not understand you can try finding an
expert to explain the issue, such as one of the authors in the paper with which
you are having problems.
Good luck with your quest!
Papers on "cockroach AND circadian" found on MEDLINE 7/4/2000:
Bult, R. and H. A. Mastebroek (1993). “Circadian control of visual information
processing in the optic lobe of the giant cockroach Blaberus giganteus.” J Biol
Rhythms 8(4): 311-23
Colwell, C. S. and T. L. Page (1990). “A circadian rhythm in neural activity can
be recorded from the central nervous system of the cockroach.” J Comp Physiol
[A] 166(5): 643-9
Eesa, N., L. K. Cutkomp, et al. (1987). “Circadian change of dichlorvos
lethality (LD 50) in the cockroach in LD 14:10 and continuous red light.” Prog
Clin Biol Res: 265-79. 227a
Ferrell, B. R. and B. G. Reitcheck (1993). “Circadian changes in cockroach
ommatidial structure.” J Comp Physiol [A] 173(5): 549-55
Lavialle, M., C. Chabanet, et al. (1989). “The 24-h rhythm of metabolic activity
of the cockroach circadian pacemaker.” Neurosci Lett 105(1-2): 86-90
Lin, T. M. and H. J. Lee (1996). “The expression of locomotor circadian rhythm
in female German cockroach, Blattella germanica (L.).” Chronobiol Int 13(2):
81-91
Page, T. L. (1981). “Effects of localized low-temperature pulses on the
cockroach circadian pacemaker.” Am J Physiol 240(3): R144-50
Page, T. L. (1987). “Serotonin phase-shifts the circadian rhythm of locomotor
activity in the cockroach.” J Biol Rhythms 2(1): 23-34
Page, T. L. (1990). “Circadian rhythms of locomotor activity in cockroach
nymphs: free running and entrainment.” J Biol Rhythms 5(4): 273-89
Petri, B. and M. Stengl (1997). “Pigment-dispersing hormone shifts the phase of
the circadian pacemaker of the cockroach Leucophaea maderae.” J Neurosci 17(11):
4087-93
Saunders, D. S. and E. J. Thomson (1977). “'Strong' phase response curve for the
circadian rhythm of locomotor activity in a cockroach (Nauphoeta cinerea).”
Nature 270(5634): 241-3
Sokolove, P. G. (1975). “Localization of the cockroach optic lobe circadian
pacemaker with microlesions.” Brain Res 87(1): 13-21
Stengl, M. and U. Homberg (1994). “Pigment-dispersing hormone-immunoreactive
neurons in the cockroach Leucophaea maderae share properties with circadian
pacemaker neurons.” J Comp Physiol [A] 175(2): 203-13
Vijayalakshimi, S., P. M. Mohan, et al. (1977). “Circadian rhythmicity in the
nervous system of the cockroach, Periplaneta americana.” J Insect Physiol 23(2):
195-202.
Wills, S. A., T. L. Page, et al. (1985). “Circadian rhythms in the
electroretinogram of the cockroach.” J Biol Rhythms 1(1): 25-37.
Q18: Sean McGurn writes:
could you please let me know if cockroaches fly. if so, have you heard of a
species that flies in the palm springs area.
A: Sean,
If you are in Palm Springs FL you could be seeing _Blattella asahinae_ the
recent import from SE Asia which is a very close relative to the German
cockroach. The import can fly and interbreeds with _B. germanica_ which leads
people to think that _B. asahinae_ was the wild species from which the
non-flying domesticated species was derived.
Another flying cockroach is the Cuban Roach, _Panchlora nivea_, recently
becoming common along the whole Gulf coast. It is bright mint green in color.
If you are in Palm Springs CA I do not have a clue as to what species you might
be seeing. There are several wild cockroaches of the genus Parcoblatta in which
the male flies. They are relatively inocuous and do not normally invade the
home. They congregate at porch lights as do the species mentioned above.
A picture of the beast would help a lot.
Q17: Alex Stegemann writes:
My father was drinking a Bud Light and on the last swig he discovered something
in his mouth. After he spit it out we discovered it was (what we think is) a
cockroach. About 6 minutes later, the cockroach began to move and tried to walk.
We killed it! Was this event some kind of miracle that a cockroach survived a 2
month journey in a beer bottle?
A: Alex,
Sorry, My conclusion is that your father left his beer sit for a brief while and
the roach decided to take a swig itself. No roach could have survived the
bottling process.
Q16: Larry and Jennifer Jeffery write:
I'm a Marine at Camp Lejuene down in North Carolina. I have heard many rumors
about a very large roach being found at Camp Johnson which is part of Lejuene. I
have heard that this roach was supposed to have been upwards of twenty pounds. I
was wondering if you maybe knew anything about this? If it was at all possible I
would like to get confirmation on this rumor and maybe a picture.
A: Larry and Jennifer,
Someone is pulling your leg. There is no roach even approaching a quarter of a
pound. Perhaps they are refering to a lobster which is known as the cockroach of
the sea since it is a scavenger:
http://www.bio.umass.edu/biology/kunkel/fish/lobster/lobste03.jpg
Or, they may be refering to a freshwater fish, the carp, which is also known as
a roach and could easily reach 20 pounds in weight. I do not have a picture of
the fish.
Q15: Machelle Broschart writes:
I am trying to write a paper on a type of roach that I found in my home. ... I
... cannot locate anything on flourecent green roaches. I was told that it is
rare, but I would like more info ... I have the roach in a jar, thinking to
preserve it due to its rare type. Please send more info ...
Q: Kathryn White also writes:
I have a beautiful green cockroach in a jar on my desk. I have lived in
Louisiana all my life and have never seen one like this. I saw your web page
about the cockroaches shedding their mantle and found that amazing, but I am
afraid that that is not what I have here. It has been in my jar for 2 days and
there is no color change.
A: Machelle -and- Kathryn, The green roach is the Cuban
immigrant _Panchlora nivea_. It is not rare on the mainland any more. It is
found mainly in Florida to Texas along the Gulf coast. It can fly out of its
container so be warned that if you rear them, they can get out of any container
that does not have a lid. You can find out more info by searching the WWW for
Panchlora.
Q14: Elaine and son write:
We're trying to find out if common cockroaches (say American) verbalize or make
sounds. ... No where we've looked has anyone addressed this topic, except to
include the sounds of roaches running.
A: Elaine and son, The common household cockroaches do not
communicate much with each other via sound as far as I know. Of course there are
several thousand species and I am only familiar with about 35 species first
hand.
There is one genus of cockroach _Gromphadorhina_ which is known for hissing.
This hissing is loud enough to scare a dog. The hissing cockroach is one of the
types commonly reared by cockroach fanciers, URL:
http://marlin.bio.umass.edu/biology/kunkel/Oxyhaloinae.html
Another species in the Oxyhaloinae which is commonly reared in labs, _Leucophaea
maderae_, also makes a stridulating noise when handled. This is also most likely
to scare whatever organism is trying to eat it rather than to warn its
compatriots.
Q13: Lara Beatty of Calgary, Canada writes:
A friend and I were discussing cockroaches the other day, and she claims that a
cockroach can live for about 6 years without it's head. Is this a true fact?
A: Lara,
Not true, but your friend is correct that a cockroach could live a long time,
perhaps a month, without its head. The only reason we need our head for basic
survival is:
(1) We breath through our mouth or nose and the breathing rhythm is controlled
in our brain. Cutting off our head would interphere with breathing although that
could be maintained with a respirator.
(2) Cutting off our head could lead to blood loss and a drop in blood pressure
which would result in death due to lack of blood transport of oxygen and
nutrition to our tissues.
(3) Cutting off our head would prevent us from eating and we would die of
starvation pretty quickly.
All of these reasons for dying are not present in cockroaches and many insects
in general:
(1) Cockroaches breath through spiracles which are in each body segment and the
blood does not carry oxygen to the tissues. The spiracles deliver air to each
cell of the body through a set of tubes called tracheae. The brain does not
control the breathing through the spiracles.
(2) The cockroach does not have blood pressure the way a mammal does and so
cutting off the head does not lead to uncontrolled bleeding.
(3) The cockroach is a poikilotherm or cold blooded animal. They need much less
food and a one day meal would be enough to last them a whole month as long as
they were not extremely active. Without a head the cockroach would just sit
around without doing anything much.
All this along with a cool temperature could allow the cockroach to last about a
month without need for their head, as long as they did not get infected with a
mold, bacterium or virus, which could kill them prematurely.
Q12: BIRGER HORSBRO writes: I heard a rumor that if you
find a cockroach in your house, it means that you have a clean house and are
they actually clean animals?
A: Birger,
The rumor, as many are, is 'right and wrong'.
Cockroaches clean themselves very scrupulously, as most insects do, in order
that their sensory bristles on their body walls and limbs are ready to sense any
hint of water, food, a mate or an enemy. Thirst, hunger, sex and safety rule the
cockroach life. A cockroach with a dirty exterior is not a 'lean mean machine'.
However, the cockroach GI tract can harbor all the diseases that are being
passed around in the house or neighborhood. They are omnivorous and thus would
just as likely eat a dead mouse or a bit of fallen cheese or nibble on your
house plant. They often defecate near or on the food they eat so they are likely
to pass the organisms in their GI tract to the food they are eating and the
surfaces they walk and defecate on.
While they keep their bodies clean for their own protection, they are not and
can not be 'house broken'. Think of them as an eternal puppy. The puppy will
instinctually groom itself but, if it is not out in the wild woods, its feces
will accumulate in its pen or in the home. Of course cleaning up after the
puppy is one strategy that works for a while.
You can keep a scrupulously clean home, but if there are cockroaches in the
building they will seek out food and water and your apartment or kitchen/pantry
may be the best place to find the small amounts of food they need to survive.
Seeing a single cockroach may be a sign that the population is low because
there is only a very little waste food around to support a small roach
population.
I hope this sets the rumor straight.
Q11: Terri Lamb asks: I was told that lobsters are the
"roaches of the sea". Therefore, I was under the impression that roaches are
crustaceans. Is this at all true? And if it is not true, what is the
relationship between a roach and a lobster?
A: Terri,
As both a lobster and roach lover I can give you a reasonably authoritative
answer. If you go to the Tree of Life WWW page at the level Arthropod
(Phylum), you will see that cockroaches are insects (Class Hexapoda) and
lobsters are decapod crustaceans (Class Crustacea); they are two groups in the
same phylum, URL:
Tree of Life (at Arthropoda level)
You can move up the tree to see how arthropods are related to other animals.
Beyond classification which should reflect the lobster and cockroach
evolutionary relationship, the term 'roaches of the sea' reflects the behavior
of lobsters as omnivorous scavengers. Cockroaches will eat almost anything
organic and so will lobsters. They clean up the dead and dying plants and
animals in their environment.
So much for the delicious taste of lobster?
Q10: I aquired a colony of B.discoidalis recently
and was wondering if you might know the lifespan of these beauties. ... Bob
A: Bob,
You probably reached the right person because I did extensive culturing of
Blaberus discoidalis many years ago and I can give you some good advice on
their longevity.
Of course, my intention in those days was growing as many B. discoidalis
as I could in as short a time as possible. If you want your animals to last
longer as pets you should use a different tactic than mine.
My whole approach to rearing cockroaches was to provide large numbers of animals
of a uniform stage as well as age and therefore I also introduced the method of
regulating food availability to keep the larval stages developing synchronously
as I had published on for Blattella germanica at URL:
http://www.bio.umass.edu/biology/kunkel/ms/k1966/
Using a similar approach I obtained the following information about B.
discoidalis stadium length (i.e. length of each molting cycle).
40 +
| f 91%
| m 72%
| f/m
| 9%/28%
30 +
D |
A |
Y | o
S|
20 + o o o
| o
| o
| o ___KEY_to_SYMBOLS______
| o o -larval molt
10 + f -molt to adult female
|___|___|___|___|___|___|___|___|___|__ m -molt to adult male
1 2 3 4 5 6 7 8 9
Molt
If you can read this graph which represents the length of
each stadium from time of first feeding until the actual ecdysis (sheding of the
old cuticle), you can add up the days it would take to get from hatching to
adult. Thus, as an example, 9% of females take 8 molting cycles to get to the
adult stage and that represents 153 days. Such an adult female could live
perhaps a year longer as an adult. All of this takes place at 30C the optimum
temperature for growth and reproduction. If you wanted to slow it down you
could lower the temp to 25C and you would double all the times (approximately).
Q9: I am graduating in Assumption University (Thailand) . I
am making a research about American cockroach life cycle. I would like to know
more information about: (1.) how long the female cockroach takes to be pregnant;
how long it can pregnant again after it produces the first egg case; and how
many cases that can be produced per time; (2.) how many eggs in each case; (3.)
how many times that the nymph can shed the skeleton; how long it takes for
sheding at the first time; and how long it can shed again after the first
sheding; (4.) what is the size and weight of nymph when its age is 6 months and
8 months; (5.) how old is the female cockroach can mate with the male at the
first time.
Ms. Raevadee Nopsuwanchai
A: Raevadee,
You have asked a question a bit more detailed than the average. The information
you ask for depends on details of the American cockroach, _Periplaneta
americana_ life cycle which are not published in one place. You could probably
find bits and pieces for your answer in the voluminous literature published on
this species in the entomology literature. However, I did some reseach on this
species in the early 1970's which I can share with you. My intention was
growing as many _P. americana_ as I could in as short a time as possible. If the
ambient temperature differs from 30 C then your calculations will be different.
My approach to rearing cockroaches was to provide large numbers of animals of a
uniform stage as well as age and therefore I introduced the method of regulating
food availability to keep the larval stages developing synchronously as I had
published on for _Blattella germanica_ at URL:
http://www.bio.umass.edu/biology/kunkel/ms/k1966/
Using a similar approach I obtained the following information about _P.
americana_ stadium length (i.e. length of each molting cycle).
25 +
| m m
| m f f
| (m/f=31%/20%)*
| (m/f=68%/70%)*
20 + (m/f=1%/4%)*
|
| n
| f
| n
15 + n
D | o o
A |
Y | o
S|
10 + o o
| o o o
| o o o ___KEY_to_SYMBOLS______
| o -larva to larva molt
| n -larva to nymph molt
5 +___|___|___|___|___|___|___|___|___|___| f -nymph to adult female molt
1 2 3 4 5 6 7 8 9 10 m -nymph to adult male molt
* -percentage f or m to adult this molt.
Molt DAYS = days from feeding to ecdysis.
If you can read this graph which represents the length of
each stadium from time of first feeding until the actual ecdysis (sheding of the
old cuticle), you can add up the days it would take to get from hatching to
adult. Thus, as an example, 70% of females take 9 molting cycles to get to the
adult stage and that represents (8+8+8.5+9+9.5+10+12+16+23) = 104 days. Such an
adult female could live perhaps a year longer as an adult. All of this takes
place at 30 C, the optimum temperature for growth and reproduction. If you
wanted to slow it down you could lower the temp to 25 C and you would double all
the times (approximately). The adult female would take about 9 days to produce
an ootheca containing about 12-16 eggs. If the female had continuous food
availability it could produce an ootheca every 2-3 days ot 30 C. The newly
hatched larva weighs about 2 mg and doubles its weight at each larva-larva molt.
So after molt 1 the larva weighs 4 mg, after molt 2 ... 8 mg and so on. Weight
for a typical adult female is given in the Kunkel (1966) paper. You should refer
to it for your research paper. Weight gain subsides at the larva-to-nymph and
nymph-to-adult molts as more energy is put into transformation toward the adult
form.
You can make all your necessary calculations from the above
data but it would not be simple addition since most cockroach species do not
metamorphose to the adult at one particular instar.
Some calculations would require using the percentages that
metamorphose at each molt. Good luck!
Q8: What is the best, non-toxic way to kill cockroaches? I
have a five-year-old boy and a pet rat that get into everything.
A: I often tell people that I am not interested in killing
cockroaches but rather learning about their life style and physiology. I
realize however that most people are more interested in killing them since they
are pests in their houses and can contribute to spreading disease in hospitals
and childhood asthma in the home.
Beware of most commercial preparations, even those that depend upon the
'natural' insect juvenile hormone. Since these are relatively slow acting, the
manufacturers often add a 'knock-down' additive poison which gratifies the user
since it provides visual proof that the treatment works when it comes in direct
contact with the pest. Read the label of whatever poison you use.
I have come across several methods of killing cockroaches that are non-toxic to
humans:
(1) Boric Acid. The crystals of boric acid are sharp and get between the joints
of an insect's exoskeleton. The sharp crystals abrade the cuticle and make the
cockroach lose water and die of dehydration. This is a simple and cheap method.
Dust the boric acid (which is relatively non-toxic) around the corners of rooms
and in hiding places frequented by the roaches. A more expensive industrial
version of this method is called Permadust. It is finely ground ruby dust which
performs the same function as boric acid crystals but is more permanent. Boric
acid washes away when you want to get rid of it. You will find the dried
carcasses of cockroaches in various hiding places as well as out in the open
where they marched their last step searching for water.
(2) Live Traps. Take a bowl or wide mouth bottle with steep sides; lightly
Vaseline the inside wall up to the lip so that a cockroach can not climb up the
slippery surface; place the bowl in a typical hiding place such as under your
kitchen sink; place some food (bread, carrots, etc.) in the bowl as well as some
toweling dampened with water; build some ramps up to the lip on the outside with
paper toweling to encourage the cockroaches to easily enter the bowl. This trap
will quickly overnight accumulate a good sample of your household cockroach
population. Flush them down the toilet each morning for sanitary disposal.
Soon the cockroach population will be quite low and perhaps undetectable by you.
This later method would also provide your pet rat a non-toxic feeding station
and your son a place to learn about the local fauna. I would not be suprised if
the pet rat ate some of the captives which are good sources of protein and
vitamins.
Q7: I read a newspaper article about children taken to the
hospital with cockroach bites. Do cockroaches bite humans?
A: The cockroach is an omnivore, that is, it eats everything
edible, animal and vegetable. So if we do not move around too much while
sleeping they might be inclined to nibble on our earlobes at night. They are
rarely aggressive enough to attack us while we are awake. When visiting Tulane
University in New Orleans many years ago I slept in a dormitory room and
cockroaches were flying down from the ceiling onto my head. I would guess that
these large American cockroaches, _Periplaneta americana_, would be capable of
taking a good bite out of me. Only the larger species could take a bite through
our skin. Of course the skin of children is much more tender and vulnerable to a
roach bite.
Q6: Why do cockroaches die on their backs?
A: First, few cockroaches die on their backs in the wild.
Natural death of cockroaches probably occurs in the stomach of a bird, bat or
other small animal.
Second, Cockroaches are not used to living on a polished marble or vinyl floor.
They are more used to a ruguous living plane including leaves and sticks and
other vegetable debris. Thus when a cockroach finds itself on its back (by some
mistake in its orienteering) it may have trouble righting itself if there is not
debris around to grab hold of with its legs. (Try it, put a cockroach on its
back on a polished floor with and without some crinkled paper.)
Third, often we come across dead cockroaches in buildings that have died of
insecticide. Most of these insecticides are organophosphate nerve poisons. The
nerve poison often inhibits cholinesterase, an enzyme that breaks down acetyl
choline (ACh), a neurotransmitter. With extra ACh in the nervous system, the
cockroach has muscular spasms which often result in the cockroach flipping on
its back. Without muscular coordination the cockroach cannot right itself and
eventually dies in its upside down-position.
Q5: Are cockroaches resistant to radiation?
A: I have been told that cockroaches are more resistant to
radiation and in a world nuclear war, only the cockroaches would survive. But I
have not seen any publication that discusses it with any credibility. I can give
only an opinion of my own. I have irradiated cockroaches and constructed killing
curves for them using gamma irradiation. I have not compared their resistance to
radiation with any other organism using the same equipment and thus can not
comment on any relative resistance based on hard data.
My opinion is that insects in general would be relatively resistant to radiation
compared to non-insects, or non-arthropods more strictly. The lives of insects
and other arthropods revolve around their molting cycles. During a molting cycle
the cells of the insect divide usually only once. This is encoded in Dyar's
Rule, i.e. insects double their weight at each molt and thus their cells need
divide only once per molting cycle.
Now it just so happens that cells are most sensitive to radiation when they are
dividing. That is the basis on which radiation is used to kill cancer cells.
Cancer cells tend to divide more often than the other cells of our body. For a
given dose of radiation you will kill more cancer cells than normal cells. With
the right dose with the right cancer you can kill all the cancer cells while
only killing some of the most rapidly dividing normal cells (i.e. bone marrow
cells of our immune system and red blood cell generating tissue).
Now if a typical cockroach molts at most once a week, its cells usually divide
within a 48 hour period within that week. That means that about 3/4 of the
cockroaches would not have cells that are particularly radiation sensitive at
any one time. If a killing radiation is endured by a cockroach and human
population, then 3/4 of the cockroaches might survive while none of the humans
might survive since our blood stem-cells and immune stem-cells are dividing all
the time.
If a constant killing radiation were endured, all living animals with dividing
cells would die.
Q4: Do cockroaches sleep?
A: Yes, cockroaches do sleep, if you define it that way.
Cockroaches have activity rhythms, i.e. regular times in the day when they are
quiet and hide away from the rest of the world as well as wakeful times when
they are active, seeking food, water and a mate. The subject of cockroach
activity rhythms is well represented in the scientific literature (see my
cockroach bibliography). In general, most pest species of cockroaches are active
(i.e. awake) during the four hours after lights-out. That is why they are often
visible when you go to the refrigerator for that midnight snack or come home
late from the movies. They cue on that time when you normally shut off all the
lights and go to bed. That ensuing four hours of activity is enough for them to
get all their important business done without the high probability of running
into you. I showed, in my first published paper, that one four hour stretch of
food availability was enough to get them through an entire molting cycle of
about 6 days. In a high density cockroach infestation the population may be
forced to come out at other times to find food. If you have lowered the
population down by using insecticides, whether that is a commercial insecticide
or your boric acid application, the remaining few cockroaches will be satisfied
with the four hour stretch after lights-out and you will rarely see them.
While we sleep they are active; while they sleep we are active.
How convenient!
Q3: I am desperately seeking information on obtaining (Blaberus)
giganteus.
A: I collected Blaberus giganteus in the garbage dump
in Key West, Florida, 25 years ago. I am told by my son that the garbage dump
is no longer accessible. Basically, in Florida or the Caribbean, you should
look for some Palm trees with a lot of leaf litter below and look under the
litter. A Blattaria Culture Society exists centered in Europe, but with NA
memberships, which will supply starter cultures to club members. Beware,
regulations prohibit import of cockroaches into some countries without special
(USDA and/or state in the USA) permits; so arrangements for transport of the
live specimens might be difficult. Finding a local enthusiast willing to share
is your best bet.
Q2: .... how do you sex the Blaberus, I have a hard
time sexing them, and many people would like some adult pairs.
A: Count the segments on the ventral surface of the male and
female abdomen. The number of visible segments is higher in the male than the
female. Also the females posterior abdomen is broader and more rounded than the
male.
Q1: I am sort of interested in why wildtype males have
shorter wings than wildtype females... Could u tell me why???
A: Wild type male cockroaches in general do not have shorter
wings than females in proportion to their bodies. In general cockroach females
are more robust than males to allow for producing and carrying their large
clutches of eggs. Thus the females tend to be larger, for example in my
illustration of
Blaberus giganteus, AND THE FEMALE'S WINGS ARE THUS LARGER THAN THE MALE
WINGS IN AN ABSOLUTE SENSE ONLY. Some of this larger size is because females
undergo more molts to get to the adult stage. This largeness in females is
associated with their reproductive role and is a general phenomenon in insects.
There is another phenomenon called brachyptery (short wingedness) which is
associated with some cockroach species as a sexual dimorphism. The females of
some species have strongly reduced wings which are useless for the gliding type
of flight that cockroaches do. (Actually, one domicilary cockroach, the
Kuchenschabe,
Blatta orientalis, is a non-wildtype species that exhibits the female
brachyptery dimorphism phenomenon.) This phenomenon is also related to
reproduction in my reading of the literature. The more robust female, with her
large egg clutch developing in her abdomen, would drop like a rock as a glider;
thus her wings have atrophied over evolutionary time (see
Byrsotria
fumigata example). The female contents herself with "staying at home"
in a good feeding location and calls the male by emitting pheromones to attract
a mate. It is the more gracile males' function to be attracted to the female
over long distances and use its wings to glide down to her from the height of
some bush or tree.
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