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How to Get Rid of Cockroaches: The Professional Method

German cockroaches are the #1 household pest problem in the US. The good news: professionals eliminate them with $30 of gel bait. Here's the exact method they use.

Ask Pestwick about this guide

8 min read · Updated January 2025

What does it look like?

German cockroaches are 1/2 to 5/8 inch, tan to light brown with two dark parallel stripes behind the head. American cockroaches are 1.5 to 2 inches, reddish-brown with a yellowish figure-8 pattern behind the head. All have flattened bodies, long antennae, and 6 spiny legs.

Similar Pests

Crickets have large hind legs for jumping. Ground beetles are harder-shelled and don't infest indoors. Water bugs (giant water beetles) are aquatic and don't infest homes regularly.

Signs of Infestation

•Small dark droppings resembling black pepper or coffee grounds in cabinets, drawers, and behind appliances
•Egg cases (oothecae) — tan, pill-shaped capsules 1/4 to 1/2 inch long
•Musty, oily odor in heavily infested areas
•Shed exoskeletons (molts) in hiding spots
•Live roaches scattering when lights are turned on at night
•Smear marks along walls from body oils and feces

Where to look

Key Inspection Areas

•Behind and under refrigerators, stoves, dishwashers, and microwaves
•Inside cabinets, especially near plumbing and hinges
•Behind wall outlets, switch plates, and inside electrical panels
•In drainage systems, sewer lines, and floor drains
•Cracks and crevices in bathrooms, kitchens, and basements

When to Inspect

Inspect at night when roaches forage (turn lights on suddenly to spot them). Check during the day in heavy infestations. Monitor year-round indoors. German roaches reproduce rapidly (inspect weekly if suspected).

Inspection Tools

Flashlight, sticky traps to monitor activity and identify species, inspection mirror, screwdriver to remove outlet covers, gloves

Treatment plan

Confirm the species

German cockroaches are small (0.5 inch), tan/brown with two dark stripes on their head. American cockroaches are large (1.5 inch) and usually enter from outside. Treatment differs.

Stop using sprays immediately

Repellent sprays scatter roaches and push them away from gel bait. This is the #1 mistake homeowners make. Stop all spray use before baiting.

Apply Advion gel bait

Apply small pea-sized dots (not smears) in every crack, crevice, and corner — under sinks, behind appliances, inside cabinets. Don't skip areas.

Apply IGR (insect growth regulator)

Spray Gentrol IGR throughout the kitchen. It sterilizes surviving roaches and prevents eggs from hatching, breaking the breeding cycle.

Apply CimeXa dust in voids

Puff CimeXa dust into wall voids, behind outlet covers, and inside cabinet hinges. Silica gel kills any roaches that touch it for up to 10 years.

Deep clean

Roaches need grease and food residue. Clean behind the stove, refrigerator, and under sinks. Fix any water leaks — roaches need moisture.

Inspect and reapply at 2 weeks

Replace depleted bait dots. You should see 80–90% reduction in roaches. Repeat IGR application at 30 days.

How to prevent it

1Keep kitchen spotlessly clean — wipe counters, sweep floors, and wash dishes immediately after meals
2Store all food in airtight containers; never leave food, crumbs, or dirty dishes out overnight
3Take out trash daily and keep trash cans clean and tightly sealed
4Fix leaky pipes, faucets, and drains — roaches need water to survive
5Seal cracks and crevices around cabinets, baseboards, pipes, and appliances with caulk
6Remove clutter, especially cardboard boxes and paper bags that provide harborage

Seasonal Note

Roaches breed year-round indoors. German roaches can go from egg to adult in 36 days — constant sanitation is critical.

Common questions

Are cockroaches dangerous?

Yes. They carry Salmonella, E. coli, and other pathogens on their bodies. Cockroach allergens are a leading trigger of childhood asthma, especially in urban areas.

How do cockroaches get into clean homes?

Mainly through grocery bags, cardboard boxes, used furniture, and neighboring apartments. German cockroaches spread through attached housing very easily.

What is the fastest way to kill cockroaches?

The fastest complete elimination is the bait + IGR method. You should see dead roaches within 24–48 hours of placing gel bait, with near-complete elimination in 3–4 weeks.

Do cockroaches bite?

Rarely. German cockroaches can bite sleeping humans in severe infestations, but this is uncommon. More significant is their role as disease vectors and allergen producers.

Can cockroaches live in a cold house?

German cockroaches prefer warmth (70–90°F) but can survive at lower temperatures. Cold alone won't eliminate an infestation. They hide in warm spots like behind refrigerators.

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