Cockroach Eggs: A Complete Guide
Cockroaches are known for being fast reproducers. Finding even one cockroach tends to be a bad sign that a major infestation could already be happening in your home or commercial building.
Female roaches already have an edge in building their populations since some can reproduce through parthenogenesis, which means they don’t even have to mate. On top of making new roaches at will, they also have the advantage of laying special eggs designed to protect the unborn nymphs from predators.
While roaches may not be fun to discover in your house, they do have interesting reproductive habits that can yield insights into how to control an infestation.
What Does a Roach Egg Look Like?
What people see as a roach egg is a little case called an ootheca. The case is made of a leathery material that is meant to be tough enough to keep out predators and protect the developing embryos from toxins in the environment, such as those pesticides you might spray around the house.
If you were to look inside the case, you’d see two rows of tiny embryos that face each other while they grow. On the outside of the case are little lines, with one long ridge running the full length of it called a keel.
When the roaches are ready to hatch, they’ll grow big enough and begin swallowing air to help them break through the keel and begin their lives as nymphs. After the nymphs hatch, the keel can close back up. This can make it hard to tell if an egg is active when you find one in a building.
Always treat roach eggs as if they could hatch at any time. Leaving even one behind could cause you to deal with a rapidly growing infestation.
How Many Babies Are In a Roach Egg?
Egg cases can hold between 16 to 50 eggs inside, with each egg responsible for developing into a single nymph. Depending on their species, roaches drop eggs around every four to eight weeks.
Considering that a typical roach has a life span of between six months to a year, it is easy to see how the reproduction rate can quickly get out of control. It is common to discover multiple generations of cockroaches, all at various reproductive cycle stages living in the same place.
German cockroaches are especially known for their exponential population growth, since their life cycle from being an egg to a fully reproducing adult only spans about 100 days.
Can You Tell the Type of Cockroach By Its Egg?
The discovery of a cockroach egg can give a savvy pest technician a clue as to which type of cockroach species is inhabiting a space.
For instance, female German cockroaches might be considered excellent mothers since they carry their egg cases around with them until just before they hatch. Since their cases are usually attached to their bodies, finding one often means it is no longer active. However, they tend to be brown and around 8 mm long.
American cockroaches also lay brown egg cases, but they can take on a black color after a couple of days. This species may carry the cases around for about a week. Still, they’ll attach them to a secure location with a special glue made from their saliva for the rest of their incubation period.
Oriental cockroach egg cases are a dark reddish-brown hue and tend to look puffed up and inflated compared to other types. They are also larger and usually range from 8 to 10 mm in length. With this species, the mother roach will quickly move her egg case to a safe location once it drops. Typically, this means a place that is located near a food source.
Where Do Cockroaches Lay Their Eggs?
While the German cockroach might try to hold onto her egg case for as long as possible, the others choose to put them somewhere else that is safe. Typically, a cockroach mother will leave the egg case near a food source so the nymphs can start feeding immediately.
Some cockroaches look for covered humid areas and away from potential predators. Others prefer to leave their eggs on dry surfaces such as cardboard.
You can usually find egg cases inside cabinets in the laundry room, kitchen or bathroom. A roach might also use a crack or crevice to protect the egg case further, so carefully check the seams of shelves and other hidden spaces.
People often discover egg cases when they start deep cleaning their homes. Sometimes, roaches leave their eggs behind large appliances such as the refrigerator or stove. You might also find them around drainage areas that give the nymphs moisture once they emerge.
Depending upon the cockroach species, some mothers leave their egg cases in the same place, which can create the appearance of clusters.
How Long Does It Take Cockroach Eggs to Hatch?
The incubation period for roaches is also species-dependent. German cockroaches have an incubation period of about 28 days, which means the mothers carry those cases around for almost a full month.
American cockroaches take about 44 days to emerge from their cases, considering that they are one of the biggest types to infest houses. Naturally, those big bodies need more time to mature.
Oriental cockroaches take the longest to leave the comfort of their cases. They have a 60-day incubation period and tend to be selective about even laying eggs if it’s too cold outside for their comfort.
When Can a New Cockroach Start Laying Eggs?
When nymphs emerge from their cases, their new life is just beginning, but they still have a long way to go before reaching sexual maturity.
During the cockroach life cycle, a nymph will molt several times, and the time between each molting is called an instar.
For many roaches, the number of instars can vary even among members of the same species. German cockroaches typically go through about six instars before they become adults. Usually, a nymph will go through this process and begin being able to lay eggs in around 60 days.
The American cockroach might go through six to 14 instars before becoming an adult. The time from being an egg to achieving full reproductive status can take as long as 600 days. Once they mature, this type of cockroach can be actively reproducing for over a year.
Oriental cockroaches go through about eight or nine instars, which can take over a year to complete. Adult females tend to live and be able to reproduce for around six months.
How to Get Rid of Cockroach Eggs?
Considering that a single egg might be harboring dozens of future cockroach babies, you want to eliminate any that you find. You have several options for handling egg cases, and these strategies will help ensure your property stays pest-free.
Remove the Egg From Your Property
Getting rid of a single egg isn’t too hard. You can wear gloves to pick it up and place it in a sealable plastic bag. Once the egg case is in the bag, you can crush it to destroy any developing nymphs before they hatch, hopefully. However, this can also release nymphs into the wild that might be almost ready to emerge.
If you choose to throw away an egg case, try to do so away from your house. Leaving the sealed bag in a garbage can by the curb can help prevent hatchlings from getting on your property. Some people also wrap the egg case in toilet paper and flush it down the sewer lines.
Dry Them Out
Sometimes, you might want to ensure the egg is no longer viable. In this case, you can use a desiccant powder to dry it out. Diatomaceous earth is one type you can use to dry out eggs, but you’ll still need to dispose of the cases.
Stop the Reproduction Process
Finally, the best way to get rid of egg cases is to stop them from being produced in the first place. Spraying for roaches not only targets the female egg layers but can also destroy their ability to create viable eggs.
Certain insecticides are designed to disrupt chitin production, a major component of the roach’s exoskeleton. Without chitin, the eggs can’t develop to maturity, which is helpful when you are still treating an active infestation.
When you see a cockroach egg, you can trust that there will be many more to come if you don’t do something right away. Always take an egg sighting as a sign that you need to do a full inspection to ensure that it isn’t just left over from a former infestation. Getting rid of eggs begins with eliminating the roaches that lay them so you can return to enjoying your cockroach-free home.