- Cimex lectularius, commonly known as the common bed bug, is a small, parasitic insect belonging to the order Hemiptera (true bugs) and the family Cimicidae. It is a hematophagous ectoparasite, meaning it feeds exclusively on the blood of warm-blooded hosts, primarily humans, but also other mammals and birds. This species has a cosmopolitan distribution, found in nearly every part of the world, and has coexisted with humans for thousands of years—records of infestations date back to ancient Egypt and Greece. In modern times, C. lectularius has re-emerged as a significant pest due to increased international travel, insecticide resistance, and urbanization.
- Adult Cimex lectularius are oval, dorsoventrally flattened insects, measuring about 4–6 millimeters in length and 1.5–3 millimeters in width. Their bodies are reddish-brown, turning darker and more elongated after feeding. They lack wings, having only small, vestigial wing pads, and their flattened shape allows them to hide in narrow crevices, such as mattress seams, bed frames, furniture joints, and wall cracks. The head bears a pair of short, four-segmented antennae, and the compound eyes are relatively small. The mouthparts are adapted for piercing and sucking; the proboscis (rostrum) is long, segmented, and tucked under the head when not in use. During feeding, it is extended forward to pierce the skin of the host and draw blood.
- The feeding process of C. lectularius is highly specialized. Bed bugs are nocturnal feeders, typically emerging at night when their hosts are asleep. They are attracted by body heat and carbon dioxide exhaled by humans. Using their stylet-like mouthparts, they pierce the skin and inject saliva containing anticoagulants and anesthetics, which prevent blood clotting and reduce pain during feeding. A single meal may last 5 to 10 minutes, during which the insect ingests up to six times its body weight in blood. After feeding, bed bugs retreat to their hiding places to digest the meal and molt or reproduce.
- The life cycle of Cimex lectularius involves incomplete metamorphosis, consisting of egg, nymph, and adult stages. Females lay 200–500 eggs during their lifetime, depositing them in hidden cracks or crevices near resting areas of the host. The eggs are small (about 1 mm long), whitish, and sticky, adhering to surfaces. They hatch within 6–10 days under optimal conditions. The emerging nymphs resemble miniature adults but are translucent and lack pigmentation until after their first blood meal. Nymphs must feed on blood to molt, passing through five instars (stages) before reaching adulthood. Under favorable conditions—temperatures around 25–30°C and access to hosts—the entire life cycle can be completed in five to eight weeks. Adults can survive for several months without feeding, and under cool conditions, even up to a year, making eradication particularly challenging.
- Reproduction in C. lectularius occurs through a process known as traumatic insemination, a unique form of mating among bed bugs. The male pierces the female’s abdominal wall with his intromittent organ and injects sperm directly into her body cavity rather than through the reproductive tract. The sperm then migrates through the female’s hemolymph to reach the ovaries. Although this process can cause physical damage and stress to the female, it has evolved as an efficient reproductive strategy within the species.
- Bed bugs are not known to transmit diseases directly to humans, but their bites can cause itchy, red welts, allergic reactions, and secondary skin infections due to scratching. Infestations also lead to psychological distress, insomnia, and anxiety in affected individuals. Their presence in homes, hotels, and transportation systems poses economic and public health concerns. The resurgence of C. lectularius in recent decades has been attributed largely to insecticide resistance, particularly to pyrethroids and organophosphates, as well as increased global travel and changes in pest control practices.
- In terms of ecology, Cimex lectularius is a highly adapted synanthropic species, meaning it lives closely with humans and depends on them for survival. It typically hides within 1–2 meters of its host’s resting area, emerging only to feed. Though primarily associated with human dwellings, bed bugs may also infest bird nests, bat roosts, and domestic animal shelters, especially in rural or abandoned structures.
- From a scientific standpoint, C. lectularius has become a model organism for studying insect physiology, host-parasite interactions, and insecticide resistance mechanisms. Genomic and biochemical studies have revealed how this species adapts to human environments, tolerates starvation, and resists chemical control, offering insights into pest management strategies.
