Cimex lectularius
Arthur C. Huntley M.D.
Dermatology Online Journal 5(1):6


Cimex lectularius, the common bed bug, is a bloodsucking nocturnal parasite of man. Other hosts for this bug include chickens, bats, and some domestic animals. Cimex feeds by piercing the host with hollow tubes derived from the maxilla. Saliva injected at the time of feeding is associated with local and sometimes widespread urticaria. This pest has become less important over the last half century with general improvements in household and personal cleanliness.

Figure 1. Cimex letularius.[1] The color has been described as rust to mahogony. The body is covered with microscopic hairs resulting in a banded appearance when engorged, revealing hairless areas (the conjunctivae between the segments). The antennae have four segments and arise from between the pair of compound eyes (not well shown). They have a joined beak or proboscis situated beneath the head and passing backward to between the coxae of the forelegs.


The bed bug, Cimex lectularius, is a true bug belonging to the family Cimicidae. The name Cimex is derived from the common Roman name for this insect. The adult is brown, flattened, oval, wingless and about 4mm to 5mm in length when unfed. Newly hatched bugs are tan and somewhat translucent. When fed, the body becomes swollen and elongated and the color becomes dull red to darker brown.

There are three species of bed bugs that commonly attack man. Cimex letularius, the most common, may also use other hosts, including bats, chickens and occasionally other domestic animals. Cimex hemipterus is apparently confined to tropical regions (including Florida) and may also infest chickens and bats. Leptocimex boueti attacks bats and humans in West Africa.[1]

Bed bugs hide in the bedclothes, mattresses, springs, bed frame, cracks and crevices of the building, and under wallpaper. They become active at night traveling to the host for a blood meal lasting about 5 minutes, and then return to their lair. They tend to congregate, and are usually found with fecal material and eggshells, surrounded by a characteristic, sweet-smelling odor, which may become offensive in massive infestations. Bedbug infestation is diagnosed by identification of specimens collected from the residence.

Bedbugs depend on blood for their complete nutrition. Feeding occurs during each of 5 nymphal stages prior to moulting, and before each session of egg-laying. The bugs apparently locate the host by detecting warmth and carbon dioxide. The bug grasps the skin with the saw-toothed modified mandibles or stylets and penetrates with the two tubes that are modified maxillae. One of the tubes injects saliva containing an anticoagulant (an inhibitor of the conversion of factor X to factor Xa)[4] and the other tube is used to withdraw the host's blood. The bite itself is said to be painless, however the deposition of saliva on the abraded epidermis results in localized urticarial wheals. Common areas of the body that are affected involve the arms and shoulders. It is said that most bites result in a generalized urticaria.[5]

Although they have not been linked to transmission of any disease, they have been shown to harbor the causative organisms of plague, relapsing fever, tularemia, Q fever, and hepatitis B.[2,6] Other agents found include hepatitis B [6] The transmission of hepatitis is theoretically possible by contamination from crushing the bug, contamination from infected feces, or from regurgitation during the bite.[7] Transmission of trypanosomes has been demonstrated for bats.[8]

These pests have become less important over the last half century with general improvements in household and personal cleanliness, and with the use of effective insecticides. Resistance to insecticides has been seen and varies by region.[3] Control is achieved by thoroughly cleaning bed cloths, mattresses and pillows. Insecticide is then used to treat the bed frame, springs, slats and nearby crevices around doors, windows, and baseboards.


1) Ebeling Walter. Urban Entomology. Division of Agricultural Sciences, University of California . Berkeley. 1978 pp463-468

2) Sanders DP. Occasional Biting Pests. Agricultural publication G07396. University Extension, University of Missouri-Columbia. 1998. (

3) Cha Chul-Hwan, Ham Ki-Sun, Yoon Jong-June, et al. [Insecticide resistance in bedbugs (Cimex lectularius) in Korea}. The Korean J. Parasitol 1970 8(1):2.A.7004. (

4) Valenzuela JG, Guimaraes JA, Ribeiro JM. A novel inhibitor of factor X activation from the salifary glands of the bed bug Cimex lectularius. Exp Parasitol, 1996 83(2):184-190.

5) Beary JD, Russell RC, Doggett SL. Department of Medical Entomology. Bedbugs. (

6) El-Masry SA, Kotkat AM. Hepatitis B surface antigen in Cimex lectularius. Journal of the Egyptian Public Health Associatoin. 1990, 65(3-4); 229-36.

7) Jupp PG, McElliogott SE, Lecatsas G. The mechanical transmission of hepatitis B virus by the common bedbug (Cimex lectularius L.) in South Africa. South African Medical Journal, 1983 63(3):77-81.

8) Gardner RA, Molyneux DH. Trypanosoma (Megatrypanum) incertum from Pipistrellus pipistrellus: development and transmission by cimicid bugs. Parasitology, 1988 96(Pt 3):433-47.