Bed bugs are small, nocturnal insects that feed on the blood of humans and other warm-blooded animals. These parasites have existed for thousands of years, documented since ancient Greece. Though largely controlled in the mid-20th century due to widespread insecticide use, bed bugs have experienced a significant resurgence globally over the past two decades. This comeback is attributed to factors such as increased international travel and the development of insecticide resistance.
Common Bed Bug Species
While over 100 species of bed bugs exist globally, only a few commonly interact with humans. The two main species that parasitize humans are the common bed bug, Cimex lectularius, and the tropical bed bug, Cimex hemipterus. These two species are very similar in appearance and life cycle, making them difficult to distinguish without close examination.
The common bed bug (Cimex lectularius) is found worldwide, thriving in temperate regions and human environments like homes, hotels, and public transport. Adults typically measure between 4 to 5 millimeters, resembling an apple seed. They are reddish-brown and flat when unfed, becoming more swollen and elongated after a blood meal.
The tropical bed bug (Cimex hemipterus) inhabits warmer, more humid climates, including parts of Africa, Asia, and Central and South America. In the United States, it is mostly found in tropical and subtropical regions like Florida and some other southeastern states. This species is slightly smaller than the common bed bug, reaching 3 to 4 millimeters. Both species are attracted to the carbon dioxide and warmth from sleeping humans, feeding at night.
Other bed bug relatives, such as bat bugs (Cimex adjunctus) and bird bugs, usually feed on their namesake hosts. However, if their primary hosts are unavailable or their nests are disturbed, these species can occasionally infest human dwellings and bite humans.
Distinguishing Bed Bugs from Look-Alikes
Identifying a bed bug can be challenging because many insects share similar appearances. Adult bed bugs are flat, oval, and reddish-brown. They have six legs and two antennae but lack wings and cannot fly. After feeding, they become engorged, appearing more balloon-like and darker reddish-brown.
Bat bugs are nearly identical to bed bugs in appearance, but a distinction, visible under magnification, is that bat bugs have longer fringe hairs on the upper part of their thorax. Bat bugs primarily feed on bats, only biting humans if their preferred host is absent.
Spider beetles are sometimes confused with bed bugs due to their similar size and reddish-brown color. However, spider beetles have a more rounded, hunch-backed body and longer legs, sometimes giving them a spider-like appearance. Unlike bed bugs, spider beetles do not feed on blood; they are scavengers that consume various organic materials like grains and dried foods.
Carpet beetles are sometimes mistaken for bed bugs because of their small, oval shape. While bed bugs are flat and reddish-brown, carpet beetles are often rounder and may have patterned shells with black, white, and yellow scales. Carpet beetle larvae are particularly distinct, appearing fuzzy or bristly, unlike bed bug nymphs which resemble smaller, paler adults. Carpet beetles feed on natural fibers and do not bite humans, though their bristles can cause skin irritation.
Ticks are another group of pests sometimes confused with bed bugs, both being small, oval, and capable of feeding on blood. A key distinction is that ticks are arachnids with eight legs, while bed bugs are insects with six legs. Ticks also remain attached to their host for days while feeding, whereas bed bugs feed for a short period (5-10 minutes) and then retreat. Ticks are usually found outdoors in grassy or wooded areas, attaching to hosts that pass by, and do not infest homes in the same way bed bugs do.