The adult bed bug is oval and flat. They grow to only about a quarter of an inch long. Bed bugs lack wings, so you won’t see them flying around your bedroom. Under cover of darkness, they crawl in search of blood, preferably from a human. Bed bugs use a piercing, sucking proboscis to penetrate the skin of their host. Adults are brown, but appear reddish-brown when engorged with blood.

Bed bug young look like smaller versions of their parents. First stage nymphs are colorless; with each molt, the nymph darkens. White eggs measure less than 1 mm in length, and may be laid singly or in clusters of up to 50 eggs.

You won’t usually see bed bug activity during daylight hours, but you may see other signs of bed bugs. As nymphs molt, they leave behind their shedded skins, which accumulate as the population rises. Bed bug excrement appears as dark spots, and crushed bed bugs will leave bloody marks on bed linens.