• Bat Bugs, Bed Bugs and Relatives (Colorado State University) 
• Bed Bugs and Lookalikes (PDF)(1 pp, 619.93 K, About PDF) (Connecticut Agricultural Experiment Station) 
• Is it a Bed Bug, Cockroach or Carpet Beetle (PDF) (1 pp, 63.55 K, About PDF) (New York City Department of Health and Mental Hygiene) 

Appearance of Bed Bugs (Cimex lectularius L.)

Two adult bed bugs in a petri dish (courtesy of Kim Jung)

• about the size of an apple seed (5-7 mm or 3/16 - 1/4 inch long);
• long and brown, with a flat, oval-shaped body (if not fed recently);
• balloon-like, reddish-brown, and more elongated (if fed recently);
• a “true bug” (characteristics of true bugs include a beak with three segments; antenna that have four parts; wings that are not used for flying; and short, golden-colored hairs); and
• smelly, with a “musty-sweetish” odor produced through glands on the lower side of the body.

• smaller, translucent or whitish-yellow in color; and
• if not recently fed, can be nearly invisible to the naked eye because of coloring and size.

• tiny, the size of a pinhead;
• pearl-white in color; and
• marked by an eye spot if more than five days old.

Bed Bug Life Cycle

Life cycle of the bed bug. Photo Courtesy of Stephen Doggett, Department of Medical Entomology, Westmead Hospital, Sydney, Australia

• Eggs (1mm).
• 1^st stage nymph (1.5 mm).
• 2^nd stage nymph (2 mm).
• 3^rd stage nymph (2.5 mm).
• 4^th stage nymph (3 mm).
• 5th stage nymph (4.5 mm).
• Unfed adult female.
• Unfed adult male.