Invertebrates
Bedbug
Cimex lectularius · also called bed bug, bedbug
A bedbug is a flat, seed-sized insect that spends the day jammed into a crack in your bed frame and the night drinking your blood while you sleep. For half a century it was almost gone from the wealthy world. Since the late 1990s it has come roaring back, spread by travel and resistant to the sprays that once wiped it out.
Overview
The bedbug, Cimex lectularius, is a small, wingless, blood-feeding insect. An unfed adult is about 5 mm, oval, and paper-thin — the size and colour of an apple seed — which lets it hide in the narrowest seams and crevices near where people sleep. It feeds only on blood, and can survive a year or more between meals.
Bites and biology
Bites often show as a row or cluster of itchy welts — “breakfast, lunch, and dinner” — and reactions vary from none to severe. Notably, bedbugs are not known to transmit disease; the harm is itching, lost sleep, anxiety, and, in heavy infestations, mild anaemia. Males reproduce by traumatic insemination, stabbing through the female’s body wall.
An old companion, resurgent
Bedbugs began as bat parasites in caves and switched to humans who shared those caves over 100,000 years ago. Nearly eliminated by DDT in the mid-20th century, they have surged back worldwide since the 1990s — carried by travel and used furniture, and now widely resistant to pyrethroid insecticides, so control relies on heat, inspection, and encasements.
Status
Not evaluated and increasing — one of the few animals whose problem is that there are far more of them than there used to be. A bedbug infestation is not a sign of a dirty home; anyone can bring them in.
Bedbug: common questions
How do I know if I have bedbugs?
The common signs are waking with rows or clusters of small, red, itchy bites, usually on skin exposed while sleeping, along with small dark spots of bedbug droppings on the sheets, mattress seams, or bed frame, tiny pale shed skins, and occasional smears of blood on the bedding. In a heavy infestation there can be a sweetish, musty smell. Because bites alone are not proof, since many things bite and some people do not react, confirmation means finding the bugs, their eggs, or their droppings, typically by inspecting the seams and folds of the mattress and the cracks of the bed frame with a torch.
Do bedbugs spread disease?
No disease transmission to humans has been demonstrated for bedbugs under normal conditions, which sets them apart from mosquitoes, ticks, and fleas. Their impact is still significant, in the form of relentless itching, broken sleep, stress and anxiety that can be severe, skin infections from scratching, and, where an infestation is large and long-standing, enough blood loss to cause mild anaemia in vulnerable people. There is also a real financial and social cost, in treatment, discarded furniture, and the stigma that wrongly attaches infestations to a lack of cleanliness.
Why have bedbugs made such a comeback?
Several things came together from the late 1990s. Cheap and frequent travel moved bugs and eggs between homes, hotels, and countries in luggage far more than before. The trade and kerbside recycling of second-hand mattresses and furniture spread them locally. Routine indoor insecticide spraying, common in the mid-20th century, largely stopped. And, crucially, bedbug populations worldwide developed strong resistance to the pyrethroid insecticides that had become the main weapon against them, so treatments that once worked often now fail.
Are bedbugs a sign of a dirty home?
No. Bedbugs feed on blood, not dirt or food waste, and they are found in spotless homes and hotels as readily as in neglected ones, because what they need is a sleeping host and cracks to hide in. Clutter makes an infestation harder to find and treat, but it does not cause one. Bedbugs are almost always brought in from outside, on luggage after a trip, on used furniture, or from an adjoining flat, and anyone can get them. Treating an infestation as a hygiene failure mainly serves to make people hide the problem instead of dealing with it.