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Roaches FAQs

 

1. Do Cockroaches sleep?
2. What is the best, non-toxic way to eliminate cockroaches? 
3. When applying a cockroach trap does my family have to leave the house like with pesticide applications 

4.Why do cockroaches die on their backs?
5. Do cockroaches bite humans?
6. Are cockroaches clean?
7. Can cockroaches live without their head?
8. What do cockroaches eat?
9. What color is the blood of a cockroach?
10. Do cockroaches like air conditioning?
11. What is the cockroach reproduction cycle? 
12. How many offspring can a cockroach have? 

 

1. Do Cockroaches sleep?

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. 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. In a high density cockroach infestation the population may be forced to come out at other times to find food. While we sleep they are active; while they sleep we are active.

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 2. What is the best, non-toxic way to eliminate cockroaches?

 There are several methods of eliminating cockroaches that are non-toxic to humans:
Traps: a trap will quickly overnight accumulate a good sample of your household cockroach population.  Just throw the trap away when full and soon the cockroach population will be quite low and perhaps undetectable by you.

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 3. When applying a cockroach trap does my family have to leave the house like with pesticide applications?

No, everyone and everything can stay, including goldfish, pets and children. A cockroacj trap like Trap-A-Raoch Hoyhoy is non-toxic and truly safe. Sso even people with a compromised immune system, the elderly, children and pets do not need to leave the house for any length of time.

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 4.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.

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5. 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.

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6. Are cockroaches clean?

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 populati

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7. Can cockroaches live without their head?

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.

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8. What do cockroaches eat?

Cockroaches are omnivores, like us. For the most part they will eat anything organic. Mostly they eat dead or immobile things. 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.

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9. What color is the blood of a cockroach?

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.

Cockroach female adult blood is occasionally orange. All other cockroach blood is colorless.

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10. Do cockroaches like air conditioning?

 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 +32) = 77°F so your air conditioner is probably set to cool below 77°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 temporarily unconditioned space. It is not a simple question.

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11.  What is the cockroach reproduction cycle? 

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.

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12. How many offspring can a cockroach have? 

Teh female German cockroach (B. germanica) can produce at max about 5-6 egg cases during her lifetime, each about a month apart after her own approximate 35 day juvenile phase. The timing depends on temperature and they develop most quickly at 30C. Each egg case has approximately 40 eggs so that means a single female will only produce 240 primary offspring. However most people like to scare you with the calculation of total progeny. That means understanding that only half the 240 primary offspring are females who could each also have 240 offspring half of which are females. Depending on the temperature one needs to calculate the larger number of offspring that a female can produce in a year, which is the usual number that is quoted.

The American cockroach produces 1 ootheca per 2.5-3 days with each ootheca bearing about 12 offspring. The number of ootheca in the adult life of an American roach is probably somewhere in the literature. The egg cases start being less frequent as the female gets older and some of the ovarioles become inactive such that an ootheca might only contain 6-8 eggs in later life. I presume an adult female might continue the output for 6 months (although that is a guess) so resulting in 60 ootheca x 12 = 720 offspring. The variance about this average might be quite high so I would not be surprised by actual counts of females producing 500-1400 offspring in her lifetime.

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