Most Wanted: German Cockroach

With insect behavior adapted to essentially every man-made habitat, the German cockroach, Blatella germanica, is
arguably one of the most successful endophilic pest species. Always a public health concern, the German cockroach resiliently and steadily survives as a challenging foe for pest management professionals (PMPs).

As an agoraphobic, cryptic and generally nocturnal pest, German
cockroach loci can be a challenge for PMPs. Any habitat that provides ambient space, metabolic warmth, and available water and food is an ecological niche for German cockroaches.

At 0.4 to 0.6 in. long, adults are yellowish-tan; nymphs are black with a light-colored stripe along the mid-dorsum. There are two longitudinal black, parallel bands on the pronotum of each. For both sexes, wings cover the majority of the body of adults.

[ RELATED LINK: Dos & Don’ts: Blatella Germanica ]

With three to four generations per year, each egg mass, or ootheca, contains 30 to 50 eggs. From the time the ootheca begins to form, 28 days are required for nymphal emergence. Highly fecund, each female produces three to six oothecae (placed into crevices and other micro-shelters). Both rapid population expansion and recovery are probable. With two generations per year, the potential for more than 10,000 progeny exists.

• Egg stage is 14 to 35 days.
• Nymphal stages (six to seven) are 6 to 31 weeks.
• Adult female life span is 20 to 30 weeks.
• Habitat is optimum at 90°F.
• Despite their wings, they have no flight ability.

German cockroaches are scavenging omnivores. They consume starches, greases and meats. For nutrient plasticity, necrophagous behavior periodically results.

As a mechanical vector of pathogens and potent allergen source, the German cockroach is of significant importance to public health. For PMPs, the new benchmark for German cockroach treatment is elimination through applied biology.

Dr. Mitchell, D.O., Ph.D., M.P.H., B.C.E., a board-certified physician and entomologist, is principal technical specialist for PestWest Environmental, as well as PMP’s Technical Editor. He can be reached at docmitchell@northcoastmedia.net or 515-333-8923.