Bed bugs are parasitic, blood-sucking insects that feed on living hosts and can be found in temperate climates throughout the world. The common bed bug feeds on human blood and is well adapted to our environment.

Other species are known to feed on poultry, bats and sometimes humans as well. Unlike cockroaches, they do not feed on waste, so the presence of bedbugs does not indicate an unclean home, as was believed in the past.

Often described as being similar in size and shape to a lentil, the insects have very flat oval bodies and six legs. Reddish-brown in colour, bed bugs can grow up to 5mm long and shed their skin throughout their lives as they increase in size. Finding the sloughed-off skin is one of the ways of identifying an infestation, although there are other methods.

Bed bugs are usually thought to be nocturnal, but this is a slight misconception. They feed at night, as this is when their hosts tend to be sleeping and blood – their only food source – is readily available. However, they can be seen moving around during the day, particularly when there is a large number of them in a home. They can easily be spotted by the naked eye.

The parasites tend to be most active around dawn. They find their food sources by crawling over them, by climbing walls or by dropping from ceilings. To feed, they inject hosts with an anticoagulant to stop the blood clotting, and an anaesthetic to prevent the host from noticing the bite. They then suck the host’s blood for up to five minutes before returning to their hiding place.

Reactions to bed bug bites vary. Some people will notice intense itching or raised red marks on the skin that are similar to mosquito bites. They may be grouped together as a result of the insect moving slightly while feeding. In some rare cases, there may be an allergic reaction to the bites, but large numbers of people show no reaction at all, making it hard to spot infestations.

Infestations can begin for a number of reasons. The most common is for them to be picked up in hotels, hostels or motels while travelling, and for the parasites to return home with their hosts and begin new colonies.

They can also be brought into a residence inside contaminated furniture such as beds or sofas, and have been known to migrate between apartments. Pets and birds can also bring them indoors.

Light infestations can be hard to spot if the victims have no reactions to bites. Bloodstains on sheets could indicate the presence of bed bugs, as can finding discarded skin cases. Another way is to notice the insects’ faeces. They look like tiny black dots made by a permanent marker and might be found in the joints of furniture, fabrics, mattresses, or anywhere the bed bugs are nesting.

Bed bugs can nest anywhere. You might find them in bed frames, on furniture, or in clothes that are not worn regularly. In severe infestations, they could also be found in lofts, crevices, behind pictures, and in boxes under the bed. Their size and feeding habits mean they can hide easily and will not usually be active during daylight hours, making them very hard to discover.

Getting rid of bed bugs takes time, and requires the extermination of the living insects as well as their eggs. This can be done with steam, using rubbing alcohol on wooden furniture, or with chemicals.

People often prefer to call a professional to assess an infestation and treat it appropriately. This is likely to be more successful than attempting to deal with the problem alone, particularly with severe infestations.

Bed bugs were all but wiped out in the 1940s, but their numbers are on the rise again. Increased international travel is believed to be the main reason, so it pays to be vigilant when you’re on the road. Look for signs of bed bugs in your room, keep suitcases shut and hang clothes up. That way you’ll have a good chance of not bringing any unwelcome hitchhikers home with you.