10/16/2026

German Cockroach - October 2026

Pest of the Month - Sponsored by NISUS

German Cockroaches (Blattella germanica)

A species of small cockroach, German cockroaches are roughly 0.5” long at maturity. They are typically a tan color and have two distinctive dark stripes running parallel along the back of the pronotum (head). Sometimes confused with the Asian or Wood cockroach because they look similar, one way to tell them apart is by behavior: German roaches have wings but don't fly in any useful sense and prefer the dark. In contrast, Asian and Wood roaches will fly toward a light source. Additionally, German roaches harbor indoors, while Asian and Wood roaches are outdoor pests drawn inside by lights or to scavenge.

German cockroaches are indoor pests that struggle to survive temperature extremes. They typically harbor indoors, often in cracks, crevices, and other dark, tight spaces. In homes, German roaches often hide in kitchen cabinets, under sinks, behind appliances, or near pipes; they gravitate toward warm, humid spaces with easy access to food and water. Research suggests that they rarely travel more than approximately 15 feet from their harborage when they have adequate access to resources. As a small species, they can harbor in spaces where larger roaches would not fit, fitting through cracks and openings as little as 1/8” wide. German cockroaches are typically difficult to eradicate. That difficulty stems from their rapid breeding cycle and their ability to develop resistance and/or aversion to several types of pesticides. German roaches have one of the fastest reproduction cycles of any domestic species, growing from egg to adult in 50-60 days under ideal conditions, with females able to carry an average of 32 eggs at a time.

Combating a German roach infestation takes sustained effort. Prepare your customers for follow-ups over the next 2-4 months to control the current population and any eggs that survive to produce the next generation. In multi-family housing units, performing exclusion services like caulking cracks and crevices can help prevent populations from migrating. Gel baits for cracks and crevices can help. Keep an eye out for signs of pesticide resistance, such as consumption without population decline, as well as overall aversion. Bait rotation every 3 months (in terms of active ingredients and bait matrix) will combat both resistance and aversion. Dust formulations are effective as they bind to the roach’s oily exoskeleton and can be applied behind and under appliances, in cracks and crevices, or in wall voids. Borate products are a good option because no insect population has been known to develop resistance to them, and insect growth regulators help control future generations. Educate your customers about food competition and cleaning habits that reduce their access to food and water. 

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