There’s no doubt about it -- these pests cause problems. They contaminate food, destroy paper and fabric, trigger asthma and allergies, and bring bacteria wherever they go. The most common indoor type is the German cockroach. In a year, one female German cockroach can produce up to 30,000 offspring. You'll find them in: kitchens, bathrooms, warm areas, near food and water, in clutter, behind pictures, and, of course, your nightmares.