Roaches have existed for more than 300 million years, meaning they have survived at least one mass extinction event and numerous natural catastrophes. The hardiness of these insects has led researchers to conduct extensive studies to determine why roaches have had a longer history than dinosaurs, modern humans and many other species of animals.
Why Roaches Survive
There is no single reason that accounts for the survivability of roaches. Rather, it is a combination of factors.
Roaches are Omnivores
Instead of having a specialized diet, roaches can and will eat virtually anything. Although they like many foods that humans enjoy, roaches will also eat pet food, wallpaper paste, glue from the backs of postage stamps or the flaps on envelopes, leather and bar soap. If the infestation is severe and food is in short supply, they may try to eat the wiring and electronics inside microwaves, televisions and similar devices. Roaches have been known to sample the sores on a pet or even bite humans. They have been known to eat tender skin on sleeping children.
Roaches are Secretive
Although the Asian cockroach is an exception, roaches avoid light whenever possible and are nocturnal. Furthermore, roaches prefer to nest in small spaces that are inaccessible to humans, such as in the cracks between walls and floors, underneath appliances or inside the walls. These two traits can allow roaches to avoid detection by their human housemates, and an invasion may become a full-fledged infestation before the presence of the roaches is detected.
Roaches are Adaptable
Roaches are quite good at adapting to change. Although most roaches prefer a warm climate, species such as Periplaneta japonica, a recent arrival in the U.S., tolerate cold very well. When roach traps were introduced that contained a poisoned sugary bait, the traps stopped being effective within a matter of years. Researchers found that some roaches developed an aversion to sweets to help them resist the lure of the traps, and they passed that aversion on to their offspring. Another adaptation that has presented problems is the ability of cockroaches to develop a resistance to insecticides. Tests showed that commonly used insecticides killed fewer roaches and took longer to kill them than the same insecticides applied to lab-grown specimens.
Roaches are Good Travelers
The cockroaches that commonly invade structures in the United States are not believed to be native to the country and are estimated to have begun arriving in the 1600s. Roaches can be hidden inside cardboard boxes, sacks of produce, grocery bags, purses, luggage, shipping crates, furniture, coat pockets and appliances. They can also enter a building through cracks around doors or windows, drains or openings around plumbing pipes.
The Importance of Eliminating Roach Infestations
Many humans view cockroaches with disgust, but the risks posed by roaches are much greater than feeling repulsed by them. Cockroaches have been known to carry as many as 33 different diseases, depending on the type of roach. They can spread these germs on the counters they walk across, in the foodstuffs, such as cereals or sugar, that they invade and the dishes with which they may cross. Some of the diseases that have been linked to cockroaches include E. coli, salmonella, strep and staph.
Children living in homes infested with cockroaches have a greater risk of developing asthma. The feces and decaying body parts left by roaches can trigger an asthma or allergy attack in susceptible adults as well as children. Furthermore, roaches tend to spread their feces over a variety of surfaces, and this can cause an unpleasant, distinctive odor that can even foul food.
Globally, scientists have identified approximately 4,500 different species of cockroaches, of which 30 are classified as pests. In the United States, four species of roaches commonly invade human habitations although not every type of cockroach is a problem in every state.
German Cockroach (Blattella germanica)
- Most prevalent type found in American homes
- Adults approximately 0.5 inch in length and light
- Prefer warm, humid areas, such as bathrooms and
Oriental Cockroach (Blatta orientalis)
- Dark brown
- Approximately 1 to 1.25 inches in length
- Prefer cool, humid locations
- Often found in basements and crawl spaces or living
under washing machines, refrigerators and sinks.
American Cockroach (Periplaneta americana)
- Also called palmetto bugs or waterbugs.
- 1.5 to 2.0 inches in length
- Reddish-brown color with yellow or tan bands behind
- Can fly
- Typically enter through drains
- Often found near heating ducts and furnaces
Brownbanded Cockroach (Supella longipalpa)
- Approximately 0.5 inch long
- Light gold to dark brown with yellow bands across
abdomen and near wings
- Can fly and jump
- Frequently found behind items hanging on walls, on
ceilings, in light switches, in upholstered chairs and sofas, inside electrical
appliances and near the top of closet walls and cabinets