Cockroaches have evolved to withstand a lot of abuse. They have an exoskeleton made to be hard yet flexible, which helps them withstand being crushed. They can also regrow limbs and have an immune system that allows them to break down many toxins.
There are 4,000 species of cockroach around the world, and only a few of those are considered pests. But the ones that are can be difficult to eliminate once they’re inside — so how do you kill them and keep them out of your house?
Winning at Evolution
Cockroaches are evolutionary marvels. Here are the most impressive and significant traits that help roaches survive.
A Flexible, Durable Exoskeleton
Unlike other arthropods, the layout, and properties of a cockroach’s exoskeleton is somewhat special. Instead of large, hard, and molded shells, a roach’s exoskeleton is made up of durable, overlapping plates connected together by a flexible membrane.
A cockroach’s outer skeleton is tough and durable, providing ample protection for this insect. It can withstand up to 900 times its body weight in pressure, meaning they can survive being stomped on.
Additionally, the exoskeleton’s flexibility makes it possible for cockroaches to squeeze into small, tight spaces without getting harmed — we’re talking spaces only a few millimeters wide.
Resistance to Toxic Substances
Cockroaches also have incredible immune systems. While most creatures can be poisoned, a cockroach’s immune system can break down and eliminate many different toxins, including those in pesticides and baits.
Treating roach infestations with pesticides often includes varying the pesticides used to combat their ability to withstand most toxins.
Cockroaches are likely the least picky eaters out there. They can and they will eat anything, even nonfood items, like cardboard and nail clippings. They’re one of natures best recyclers of detritus.
They also have twice as many olfactory receptors as other insects, meaning they pick up on even trace food odors. And they don’t need much to survive — dirty dishes left out in the sink overnight can provide adequate nutrition. And they can go as long as a month without food when necessary.
No Need for a Mate
While many species of cockroach mate, the American cockroach is capable of a type of asexual reproduction called parthenogenesis when males aren’t available. Parthenogenesis, or virgin birth, happens when female cockroaches (and other animals) produce eggs without the need for fertilization from a male.
How does this help roaches survive? If your roach treatments are killing off more males than females, the next generation of cockroaches can still be hatched.
Breathing through their Bodies
Cockroaches don’t have a single organ dedicated to breathing like we do. Instead, their bodies have holes, called tracheae, they use for gas exchange. The only place they don’t have tracheae are their heads.
A cockroach can can continue to survive without its head for several days before finally expiring of dehydration.
Cockroaches are fast — they can move up to 50 body lengths per second, which is the equivalent of a person running 200 miles per hour.
Cockroaches can actually regrow limbs and severed tissue — which is helpful for them, but not as helpful for anyone trying to eliminate them.
Fact or fiction? What Cockroaches can Survive
Being Stepped On: Fact
Because they can withstand up to 900 times their body weight in pressure, being stepped on will not kill them. Of course, even their tough, flexible exoskeletons have their limits, but don’t be surprised if the roach you stepped on walks off unharmed after you lift your foot back up.
Nuclear Blasts: Myth
It’s a popular myth that cockroaches can survive a nuclear blast. While roaches do have high radiation tolerance, especially compared to humans, they still have their limits.
The radiation a nuclear blast produces greatly exceeds that threshold, and it will kill cockroaches. But the force of the blast itself would likely kill them before the radiation did.
While nature made cockroaches tough to kill, fire and high temperatures seem to be their kryptonite. They’re ultra-sensitive to heat and fire. They can’t withstand temperatures, above 115 to 120 degrees F for a long period of time. This makes heat treatment a possibly effective method of getting rid of a cockroach infestation.
On the flip side, extreme cold (below freezing temperatures) also seems to be an effective way of killing cockroaches. But lowering the temperature gradually isn’t as effective as a quick change of temperature. And it also takes prolonged exposure to kill eggs.
Being Fully Submerged In Water: Fact
Cockroaches can be drowned, but it takes time — about 20 to 30 minutes depending on the species. Some cockroaches live near bodies of water and have adapted to hold their breath for extended periods of time, but they can’t do it forever.
How to Repel Cockroaches Inside your Home
Keep Your House Clean
Cockroaches enter your home in search of food, water, and shelter. The best way to keep them out is to withhold those things.
Cockroaches don’t need much and can survive for up to a month without food — so unless you can guarantee that not a single scrap of food left on dirty dishes will be available for an entire month, it’s unlikely you can entirely block access to food sources.
But you can try. Don’t leave dirty dishes in the sink overnight — cockroaches are nocturnal so cleaning up food before bed is a good strategy to implement. Pay special attention to stove tops and under ovens and refrigerators.
Sweep, mop, and vacuum regularly to keep food particles off the floor. And keep the insides of cabinets free of food crumbs as well.
But remember, cockroaches are resilient and can be found in even the cleanest of homes, so implement other strategies in combination with proper cleaning to keep them out.
Seal Up Potential Entry Points
Insects let themselves into houses through cracks in the walls and openings in corners of doors and windows. Cockroaches can take advantage of cracks that are only millimeters wide. To lessen the likelihood of cockroaches getting in, these entry points need to be sealed.
Pay attention to areas around plumbing, like those under sinks and in laundry rooms. Caulk cracks between baseboards and flooring. For holes needed for light, air, or liquids to pass through, such as sink drains, you can use mesh.
You should also pay attention to the areas around windows and doors. Use wire mesh screens and make sure to get any damaged screens repaired.
Use Cockroach Bait and Traps
While cockroaches have great poison tolerance, some substances still work, and if you vary the baits and toxins used, you might increase your chances of killing them.
A popular cockroach bait is boric acid, and it comes in powder form. Mix a tiny amount of boric acid with some powdered sugar and place them in bait stations. The powdered sugar will lure the cockroaches, while the boric acid kills them.
Make sure to use boric acid correctly. If not, it can be ineffective and a hazard to people and pets. Use only what you need and avoid mixing it with water, which will dilute it.
Alternatively, commercial cockroach baits are readily available in the market. They usually come in gel form and are formulated specifically to contain poisons roaches don’t tolerate well. You can use these gel baits on the corners of your walls, on cracks, and on crevices around the house where cockroaches hide.
Sticky traps can also be set out before bed and disposed of in the morning. Rather than poisoning cockroaches, they trap them in a glue-like substance where they eventually die.
Hire an Exterminator
Do it yourself methods can only achieve so much and are more effective on smaller cockroach infestations — before they’ve had a chance to breed. If you have a larger infestation than you can handle call pest control. They have all the right equipment, knowledge, and experience to deal with cockroaches.