Answer: The dark-brown, shiny insects you found are Blatta orientalis, or the oriental cockroach. The common name is misleading, as these large insects originated in Northern Africa, in areas with mild winters and warm summers. Sometimes called water-bugs or water beetles, these insects love moisture. They cockroaches are not as common in our homes as the European brown cockroach, but they are a little more upsetting because of their size. The females get a little larger than the males, about (3 cm) or 1 1/4" to the males (2cm) or 1". The females don't have wings, just short, stubby little wing-pads. The males have wings, but they cover only about
2/3 of the abdomen. They move rather sluggishly, and neither the males nor the females can fly.
The females carry egg capsules around for about 24 hours, then lay them in protected crevices. Eggs will hatch in two months. The nymphal stages last from mid-spring till the end of summer, so the ones you found in your sink this time of the year were last years adults. Only about one generation is produced per year. The oriental cockroach is found state-wide, and can tolerate a wide range of temperature, including periods of freezing.
As these cockroaches require moist habitats, you should check the crawl space between your floor and the soil, your water meter, or your basement if you have one. They are most often found in bathroom toilet bowls, bathtubs, kitchen sinks, and around utility pipes. The oriental cockroaches prefer starchy food, and can build up large populations around garbage cans. Damp garages with bags of pet food available are also favorite places to live.
Improving light and air circulation will help reduce their numbers, as will a thorough job of caulking any open areas through ground level walls. Check your drainage system to be certain that you do not have areas which remain moist. Clear away leaves from foundations and window wells, and cover all food sources.
Pesticides should be used with care, particularly around moisture. Roaches are a cosmetic nuisance, and keeping a really clean kitchen will easily deter them. If you must control them, use a bait of boric acid and sugar. There are doubtless many recipes on the Internet, or you can hire an exterminator.
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