Signs of Roach Infestation: How to Tell If You Have Roaches

Illustration: a sticky trap pushed into the back corner of the cabinet under the kitchen sink, lit by a flashlight.

Signs of roach infestation are pepper-like droppings in cabinet corners and behind appliances, egg cases, shed skins, a strong odor and live roaches after dark. Roaches out in daylight usually mean a large population. To confirm, set sticky traps along walls overnight: one adult suggests a newcomer, while young roaches (nymphs) of several sizes mean an established infestation.

Cost: about $10–20 in supplies. Time: about 1 night to several days. Difficulty: easy. Call a pro if you see roaches in the open during the day, your traps fill with nymphs of several sizes, or roaches keep coming from a neighboring unit after weeks of baiting.

Found a single roach? How big a deal it is depends mostly on which roach it was, and you can check for about $10 before you spend anything on getting rid of roaches. This guide covers each sign and how to read a sticky trap. We haven’t tested products ourselves; it rests on UC IPM, University of Florida, University of Kentucky, NC State and EPA guidance plus list prices.

How Many Roaches Is an Infestation?

No agency sets a number. Which roach you saw, and whether it breeds indoors, matter more, and a dead roach tells you as much as a live one:

Left: German cockroach, photo by Clemson University, USDA Cooperative Extension Slide Series (CC BY 3.0 US). Right: American cockroach, photo by Insects Unlocked (CC0). Not to scale; both via Wikimedia Commons.

German roaches breed fast, with 3 to 6 generations a year (University of Florida), so run the trap test this week rather than waiting to see more. If traps catch only the occasional big adult, you have visitors, not an infestation; door sweeps, caulk around doors and windows, and sealed pipe gaps help keep them out. Oriental cockroaches are sometimes called water bugs, so a big black “water bug” by a drain is often one of these visitors (water bug vs. cockroach).

What Does a Roach Infestation Look Like?

Roaches come out mostly at night, so you often find droppings, egg cases, shed skins or a strong smell before a live one.

Illustration: droppings along a cabinet hinge, a light-brown egg case in a crack, and a shed skin at the base of the wall behind a fridge.

Droppings plus a live roach on a trap in the same cabinet point to an active infestation. And a roach out in the open during the day means a high probability that the population is large, University of Florida entomologists say, since roaches hide by day and forage at night.

Roach Droppings: The Sign You’ll Find First

Poop is the sign you’ll most likely find: specks like ground pepper where roaches live or used to live, plus dark smears that stain surfaces. Specks last a long time, so old ones don’t prove roaches live there now. Wearing gloves, wipe the spot with hot, soapy water and look again in a few days; fresh specks mean they’re active.

Roach specks sit near food and water in kitchens and bathrooms; cockroaches seldom gather on beds the way bed bugs do. That location is the quickest way to tell cockroach poop from bed bug spotting, which looks much the same.

Egg Cases and Shed Skins: Proof They’re Breeding

An egg case (ootheca) is a small, bean-shaped capsule, about ¼ inch long for German roaches (UC IPM); the big outdoor species leave slightly larger ones. A German female carries hers until just before it hatches, while the others glue or drop theirs in hidden spots. So if a trapped German roach has a capsule sticking out of its rear end, start control now rather than waiting.

Shed skins come from nymphs, baby cockroaches that molt several times; several in one spot mean young roaches are growing there. Each egg case marks a hiding spot worth a trap. Black dots or a capsule? See roach eggs vs. roach poop.

What Does a Roach Infestation Smell Like?

A heavy infestation gives off a distinctive, unpleasant odor, strongest in closed spaces like the cabinet under the sink. A few roaches rarely make a noticeable smell, so if you can pick it out, the population is usually large. More in what roaches smell like, and smells that mean pests compares it with mouse urine and other odors.

Signs of a German Cockroach Infestation

German cockroaches are the usual indoor infestation: specks in cabinet hinges and around the stove, fridge and dishwasher, nymphs of several sizes on traps, and sightings in the kitchen and bathroom first, spreading as numbers grow. Start baiting now, as in how to get rid of German roaches.

How to Tell If You Have Roaches Without Seeing Them

Sticky roach traps are the best way to detect cockroaches, and a 12-pack of plain ones costs about $10.

Step 1: Place traps flat against walls in cabinet corners, behind the fridge and stove, under the sink, by the trash and behind the toilet: about six for a kitchen and one bathroom, plus one by an outside door. Add traps where you found droppings, skins or egg cases, and in basements by floor drains, sump pumps and crawl spaces.

Step 2: Run a flashlight along thin cracks. Adult German cockroaches squeeze into cabinet hinges, door frames and the gap where counter meets wall, and roaches hide in and under clocks, toaster ovens and anything else warm.

Step 3: With kids or pets, fold each trap into the box shape its perforations allow, and slide it behind the fridge or deep into a latched cabinet.

Step 4: Number and date each trap, and check every morning for several days; roaches are often caught within the first 24 hours. Bag used traps.

Illustration: a trap with a single adult roach (left) and a trap with adults and nymphs of several sizes (right).

Are Roaches Dangerous for Kids and Pets?

The main risks are allergens and germs. The EPA says proteins in cockroach droppings and saliva can cause allergic reactions and trigger asthma, and roaches can carry germs onto food and counters. Keep food and pet food sealed, and vacuum droppings and skins with a HEPA filter. If a child or pet gets stuck on a trap, don’t pull; NC State recommends working cooking oil or baby oil into the glue.

What to Do Next

If traps show an infestation, bait, not spray, is the main do-it-yourself tool: small dabs of gel bait in cracks near the traps that caught the most, kept deep in cracks or in child-resistant stations around kids and pets. Sprays repel roaches and keep them from eating the bait. Expect 7 days or longer before you see fewer roaches (UC IPM), and count them gone when none turn up for four weeks.

1. Identify the roach by size and color.
2. Put away food, pet food and dirty dishes tonight.
3. Set six numbered sticky traps against the walls.
4. Wipe old droppings and check for fresh ones.
5. Bait where the traps catch most, and stop spraying.
6. Keep trapping until four weeks pass with no catches.

Renting? A German cockroach infestation can spread between apartments through shared walls and pipes. Send your landlord dated photos of your trap results and ask in writing for treatment and sealed pipe gaps.

DIY: Catchmaster list prices, October 1, 2026, before tax and shipping. Pro: the middle half of 25 single-visit and 10 full-treatment quotes homeowners shared on Reddit. Price-guide range and annual plans: This Old House (March 2026).

Serious indoor infestations often need a professional (UC IPM), but not a year-long plan: the University of Kentucky says it should not take a full year if treatment is done correctly. Ask a pro to treat cracks and hiding spots rather than baseboards, where roaches spend little time, and whether you can cancel once traps come up empty.