A blood-sucking parasite that lurks unseen in the sanctuary of our cosy homes, it’s no wonder that the bed bug fills us with horror.
But before you reach for the hoover, it’s worth taking a moment to examine this most unpopular insect. It can survive months without feeding; track its human victims by detecting heat and carbon dioxide; and mates by injecting semen with a stabbing, dagger-like penis. There’s more to the bed bug than meets the eye.
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What is a bed bug?
A bed bug is a small, flightless insect in the family Cimicidae. Of the many cimicid bugs that feed on birds and mammals, two species are most important to people: the common bed bug, Cimex lectularius, and the tropical bed bug, Cimex hemipterus.
Both are obligate blood-feeders, meaning they need blood to grow and reproduce. Unlike lice, fleas or ticks, they do not live on the body. Instead, they hide close to where a host sleeps and feed when the opportunity arises.
Where do bed bugs live?
The common bed bug is found across much of the world, especially in temperate and subtropical regions, while the tropical bed bug is mainly associated with the tropics and subtropics. Both have travelled widely with people, helped by luggage, furniture, clothing and the steady movement of human life.
A bed bug usually lives close to sleeping areas. It may hide in mattress seams, furniture, bedding, cracks in walls or behind loose wallpaper. Its body is so flat that an unfed adult can squeeze into tiny crevices by day, which is partly why it is so difficult to find.
What does a bed bug look like?
An adult bed bug is oval, flattened and reddish-brown, and looks a bit like an apple pip or small brown lentil. It doesn’t possess functional wings and cannot jump either, though it can run surprisingly quickly when warm.
How big are bed bugs?
The young, called nymphs, resemble smaller, paler versions of the adult. They pass through five nymphal stages before becoming mature, and each stage requires a blood meal before moulting.
How does a bed bug find its host?
The bed bug is mainly nocturnal and is often most active before dawn when people are typically in their deepest sleep. It is attracted to the warmth radiated by their sleeping host along with the carbon dioxide exhaled during respiration (which it can detect from 90cm away). Once it reaches skin, it uses piercing, sucking mouthparts to feed.
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A meal can last several minutes. During feeding, the bed bug injects saliva containing substances that help stop blood clotting and reduce immediate sensation, which is why many people do not feel the bite at the time. After feeding, the insect retreats to a hiding place to digest its meal.
What are the symptoms of a bed-bug bite?
Some people show no obvious marks, while others develop small, itchy, red swellings that often appear in a line or cluster. The marks can take hours or days to appear. Bed bugs are not known to spread disease to people, but bites can still be distressing and some people have more severe reactions.
How does the bed bug breed?
Bed-bug reproduction is startlingly strange. The male pierces the female’s abdomen with a dagger-like penis and the sperm migrates to her ovaries – a process known as traumatic insemination. The female later lays pale, tiny eggs in hidden places such as crevices and cracks. Over her life she may produce about 150 eggs. The young hatch as tiny nymphs and pass through five nymphal stages into maturity, requiring a blood meal each time they moult.
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How long can a bed bug survive without feeding?
Adults and nymphs usually feed every few days when a host is available, but they can survive many months without a meal, especially in cooler conditions which cause their metabolism to slow down.
Are bed bugs a sign of poor hygiene?
No, they favour the presence of blood-filled hosts and the warmth of centrally heated buildings, rather than unsanitary conditions. Hotels and hostels are particularly vulnerable to infestations because bed bugs hitchhike on visiting guests, their clothes and luggage.
However, good housekeeping will of course ensure that you discover the presence of bed bugs early on, thereby increasing your chances of successful eradication.
How can you tell if bed bugs are present?
Bites alone are not enough, because many insects and skin conditions can produce similar marks. More reliable signs include live bugs, pale eggs, shed skins, dark faecal specks, tiny blood spots on bedding and, in heavier infestations, a sweet or musty odour.
How do you get rid of bed bugs?
First, you need to correctly identify the bed bugs, because they can easily be confused for other insects. A torch and magnifying glass can help you spot them in their common hiding places, such as mattress seams.
Then attempt to remove them by vacuuming these areas carefully and thoroughly, before washing and drying affected bedding and clothing on a high heat.
Consider sealing up any cracks or crevices and clearing clutter. Severe or persistent infestations often need professional pest control.
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