Seeing a cockroach skitter across the kitchen floor can cause most of us to flee or freeze. And because rarely, if ever, is there just one cockroach, it’s imperative to investigate further to find their eggs so you can deal with them before they hatch.

To help, we’ll show you how to identify cockroach eggs, where to look for them, and what to do if you find them inside your home.

What Do Cockroach Eggs Look Like?

Small but visible to the naked eye, individual cockroach eggs are the size of a speck of dust or a grain of salt.

When a female adult cockroach deposits her eggs, however, they’re encased in a cocoon-like sac called an ootheca. These hard-shelled casings vary from species to species, but most look like a pill capsule or dried kidney bean. They’re tan, russet, brown or black, ranging in size from less than a 1/4-in. to a 1/2-in. long.

An ootheca may be smooth or have ridges. Each has a seam called a keel where nymphs (immature baby cockroaches) can crack through and emerge. Once they escape, the keel closes up, leaving behind empty ootheca sacks, sunken but fully intact.

Fun fact: A newborn German cockroach matures into an adult in a little more than one month.

Do All Cockroaches Lay Eggs?

Yes. The most common species found in the United States are German, American, brown-banded and Oriental cockroaches.

Generally, an ootheca contains 16 to 50 eggs. Because an adult German cockroach can lay 200 to 300 eggs in her lifetime, or six generations a year, she can potentially produce 300,000 offspring annually. She, like a few other species, will carry around the eggs and deposit only the sacs just before hatching.

Incubation and hatching times vary wildly between species, falling between six and 115 weeks.

Fun fact: A one-day-old cockroach nymph can run almost as fast as its adult parents.

Where Do Cockroaches Lay Eggs?

Somewhere dark and damp, like cupboards, pantries, drains, basements and bathrooms. Also under furniture, the refrigerator, stove and sinks.

American and Oriental cockroaches like to leave eggs near food sources, the latter preferring warm, covered areas. The brown-banded cockroach places her eggs in clusters under furniture, in crawl spaces and in cardboard boxes.

Tip: To avoid moving cockroaches from one house to the other, carefully check boxes and other packing materials for eggs. Once you arrive at your new home, check again.

What Should You Do if You Find Cockroach Eggs?

Mark Ascerno and Jeffrey Hahn, cockroach specialists from the University of Minnesota Department of Entomology, suggest a few non-chemical ways to remove eggs and casings:

• Squash eggs: If it won’t make you queasy and it’s a small infestation, put on gloves and squish egg capsules with your thumb to kill the young inside. Then vacuum up the debris.
• Vacuum (without squishing): As soon as you see egg sacs, clean them up with a vacuum equipped with a high-efficiency particulate air (HEPA) filter. This reduces airborne cockroach debris, which triggers asthma and allergies. Afterward, seal and dispose of the vacuum bag outdoors in a trash bin.

Chemical solutions:

• Spread a powder: Sprinkle boric acid or diatomaceous earth on eggs to dehydrate and kill them.
• Soak with insecticide: Douse eggs with an aerosol roach killer. Read the label and use only as directed.
• Apply an Insect Growth Regulator (IGR): Killing the female cockroach before she deposits her eggs is the most effective way to stop cockroach procreation. IGRs act like roach birth control, preventing the growth of a cockroach’s exoskeleton and disrupting the normal development of embryos.