Final answer:
Small grains resembling black pepper underneath a sink suggest a cockroach infestation. These grains are actually cockroach droppings. Proper identification and hygiene, along with traps and insecticides, can help in controlling the problem.
Step-by-step explanation:
If you find small grains that look like black pepper underneath a sink, it's likely an indication of the presence of cockroaches. These small grains are actually cockroach droppings, which have a similar appearance to black pepper grains. Household pests such as ants, mice, and fruit flies leave behind different kinds of evidence of their presence. Mice, for example, typically leave behind larger droppings and may also leave signs of chewing or nesting materials. It's important to accurately identify the pest so you can choose the correct method to control it. For cockroaches, maintaining cleanliness, especially in areas where food is stored and prepared, is crucial for control and prevention. Keep an eye out for other signs of infestation, like live or dead cockroaches and egg cases in dark, moist areas. Use of baits, traps, and insecticides might be necessary to fully eradicate the infestation.