The German cockroach, known by the scientific name Blattella germanica L., is one of the most highly adaptable species of insect. The German cockroach primarily inhabits indoor spaces, predominantly in urban and suburban areas with dense populations. The most commonly encountered urban pest, this insect frequently resides in major cities. The United States serves as a prime region for German cockroaches due to extreme population densities, including several major cities, which provide damp and dark living spaces with adequate food sources. The pests are commonly found in apartment complexes, hotels, homes, and other commercial/residential structures throughout expanding urban areas.
What do German cockroaches look like? Relatively small in size, German cockroaches typically measure between 3/8 of an inch and half an inch long. Adult specimens generally feature tan or light-brown coloration, large wings, six legs, two long antennae protruding from the head, and two black stripes just behind the pronotum that run the length of the thorax. Males tend to have skinnier bodies with more defined abdominal and terminal segments, while females boast thicker frames, rounder abdomens, and an extra set of wings. During developmental or nymph stages, German varieties appear darker brown or even black in color.
The nocturnal insects spend most of the day well hidden in warm, dark, and damp areas. At night, the pests look for food and suitable mates. If German cockroaches are seen during the day, then the population within the structure is large enough that ideal hiding places are not available for all cockroaches. German cockroaches regularly emit a foul odor as a defense mechanism. Though the insects possess wings, they do not fly. The pests mate continuously upon reaching the adult stage. Migration patterns usually include moving from building to building, home to home, or room to room within a home. German cockroaches move on as food sources dry up and indoor climates change. The cockroaches may migrate outdoors during warm, humid summer months before finding shelter in a new building or structure once food or adequate shelter is needed.
German cockroaches are considered generalist feeders. Primary food sources include starches, fermented/rotted foods, beverage residues, and sweets. German cockroaches also eat meats and other processed foods. Garbage cans or dumpsters serve as main food sources for cockroaches, especially those left unattended.
German cockroaches reproduce by egg. Once fertilized by a male, females produce a small sack or capsule which holds between 30 and 50 eggs at a time. The egg capsule remains attached to the abodomen of the female cockroach. A healthy female produces eight capsules during her lifetime. German cockroach eggs hatch within a few days of the egg capsules creation. The insects then go through6-7 nymphal cycles lasting around 40-125 days, on average, before reaching adulthood. An adult lives from 20 to 30 weeks and produces multiple generations in a single year.
Problems Caused by German Cockroaches
The main concern humans face with German cockroach infestations is the risk of food contamination. Cockroaches notoriously congregate in garbage, mold, and other materials potentially hazardous to human health. The pests regularly inhabit kitchens and, due to eating many similar foods as humans, may spread illnesses through unattended foods. The foul odor produced by the insect is also known to change the taste of foods that have come in contact with German cockroaches. Gastroenteritis is cited as a common incident related to food contaminated by cockroaches. Other viruses and harmful bacteria may also be transmitted by the insects. Reported cases also exist of allergic reactions to cockroach shells and wastes left behind by the insect.
An average German cockroach spends most of its life in a tropical environment. They prefer a warm, humid climate, so they seek out kitchens and bathrooms.
Male roaches inseminate the females. After being inseminated, the female can produce several batches of eggs without mating again. Each batch of eggs is encased in a capsule called an ootheca.
The female roach keeps the ootheca attached to her body until the eggs are ready to hatch. She drops the capsule when it is time for the eggs to hatch. Sometimes the eggs hatch while the capsule is still attached to the female roach.
When the baby German roaches hatch, they are called nymphs. They are tiny insects. They stay hidden and feed on the droppings of the adult roaches. At the same time, the adult roaches eat many of the nymphs!
German cockroaches spend most of their life in the dark. They hide in cracks and crevices during the day. They come out briefly at night. As soon as they find food, they eat it and then run back to their hiding place.
German cockroaches can survive for several weeks without eating. They can only live without water for about two weeks. If a homeowner sets of a “bug bomb”, the roaches will hide inside the walls until they need water. This may be the reason many homeowners say that the bombs only controlled the roaches for about two weeks.
Homeowners who are starting to see German cockroaches in the daytime may have a large problem. The cracks and crevices may be getting overcrowded. The food and water may be hard to find at night. There is a reason that the roaches are being forced out of their comfortable hiding places during the day.
To eliminate the roaches, homeowners can start by eliminating the food, water, and hiding places. Little things like putting away leftover food promptly and washing dishes before going to bed can make a big difference.
Pet food should not be left out overnight — the roaches will be the ones that eat it. Bottles and cans should be rinsed before they go into the recycle bin. The recycle bin should stay outside of the house.
If there are a lot of roaches, it may help to vacuum the cracks and crevices in the kitchen. Put the vacuum bag in a trash bag and dispose of it outdoors. It may help to caulk as many of the cracks and crevices as possible, especially near the stove and sink. This will keep the roaches from hiding in them.
Any roaches that are still around can be eliminated with cockroach bait. It usually takes time for this part of the program, so many homeowners call on a pest control professional for the bait applications, the monitoring, and the follow-ups