So, what do bed bug bites look like? Bed bug bites are similar to other insect bites such as from mosquitoes and fleas.
However, one identifying factor is that they tend to occur in a line on bare skin, especially legs, arms, neck and hands.
The bites generally come in threes, which are sometimes called ‘breakfast, lunch and dinner’, so a line of three bites can be an identifying factor.
- If the bugs are disturbed while feeding they will bite multiple times in the same area and they then look like a skin rash.
People’s skin reaction to the bites varies from no reaction at all to red spots on the skin, minor skin swelling and itching. People sleeping in the same bed can have different reactions: one person can have no sign of bites and the other have itchy red spots, but both of them are likely to have been bitten.
The best way to tell that bites are caused by bed bugs and not other insects is to look for the tell-tale signs of the actual bugs.
Bed Bug Feeding Habits
Bed bugs feed every 5-7 days, only leaving their shelter to look for a host when they are starved. They tend to feed at night but if they are starved will search for a host at any time, especially if a nearby host tends to sleep during the day.
Bed bugs won’t climb over your body; they crawl along the bedding and feed where your skin comes into contact with the bed, which means the bites will be on the side of your body that you are sleeping on.
They need just 5-10 minutes of feeding to become engorged with blood and may spend less than 20 minutes on a host. After feeding, they return to their shelter — so spend most of the time there.
The bugs are attracted by warmth, carbon dioxide and various body chemicals, which means the little critters have quite a sophisticated array of sensing ‘devices’ to find a suitable body for feeding on.
Scientists have found a wide range of chemicals given off by animals attract bed bugs.
One study by the State University of New Jersey and Purdue University looking at the best mixtures for use in lures, found that a mixture of spearmint oil, coriander Egyptian oil along with some organic chemicals (nonanal and 1-octen-3-ol (octenol)) was the best at attracting the bugs. They also found that bed bugs prefer a black to a white surface. Other scientists have found other mixtures attract the bugs, but they were only tested in laboratory conditions.
Can Hairy Skin Protect You from Bites?
A study at the University of Sheffield found that hairy skin may give some advantage over smooth skin. Volunteer students had one arm shaved and the time taken for bed bugs to take the first bite on each arm measured. The bugs took significantly longer to bite on hairy skin and the victims were more likely to feel the bugs crawling around.
The students were spared from the actual bite as the bugs were removed as they were about to bite! It has been known for some time that hairiness gives a degree of protection from some insect pests, but no one had actually tested this with bed bugs before. However, hairiness is unlikely to stop the bugs from eventually biting you while you are sleeping.
Why Do Bed Bug Bites Itch?
Bites itch because your body reacts to the saliva injected by the bed bug while it is biting you.
Bed bugs, similar to other biting insects, have a complex mouth with one needle-like part that pierces the skin and other parts that are serrated and saw through the flesh to find a blood vessel.
It also has a food canal to suck up blood and a canal that injects saliva containing anticoagulant and anaesthetic.
The anticoagulant keeps the blood liquid so it keeps flowing and the anaesthetic stops you feeling the bite so you don’t disturb the feeding bug.
The body’s immune system recognises the foreign material and produces histamine as a defence mechanism. This causes localised inflammation and itching.
How Long Does it Take for Bites to Appear?
This is a bit like asking: “How long is a piece of string?”
People have different rates of reaction to the bites depending on the sensitivity of their immune system to the foreign material injected during the bite: the body can take from half an hour to several days to react to a bite. The body also learns to recognise the ingredients in the saliva so subsequent bites can produce a quicker reaction.
How did Bed Bugs Get Here?
Bed bugs like to hitch a ride with people — you are most likely to pick them up from a hotel on your holiday. They can crawl into luggage and clothing and have no problem surviving long journeys.
They can also be carried in bedding and furniture and crawl from room to room through holes in walls, such as for electrical wiring, or along pipe work. Bed bugs are pretty good at playing hide and seek. This means a thorough inspection is critical to identify where and how big the problem is.
Bed bugs give off chemicals — called aggregation pheromones — that attract others to a shelter and tell each other that a shelter is safe. The males also use them to attract females.
Recently, after five years of research, in which Simon Fraser University biologist Regine Gries endured 180,000 bed bug bites in the name of science, the final mix of the attracting chemicals was identified, including three that were not known to be present in bed bugs.
Of course, this is just one team’s findings and there are others working on this with varying accounts.
Surprisingly, one of these chemicals is histamine, which is also produced by the human body in response to insect bites. It signals to the bugs that a shelter is safe and makes them stay put.
[The research was published in the journal Angewandte Chemie International Edition, January 19, 2015 DOI: 10.1002/anie.201409890]
How to Treat Bed Bug Bites
Bed bugs are not dangerous and do not transmit disease, so there is no need to worry about more than itching or perhaps a rash.
As mentioned above, many people do not react to the bites so do not need any treatment. Also, as people’s skin reaction to the bites varies, there is no fixed period during which the bites are itchy or the time taken for the red spots to heal.
The medical community advises that if the bites develop into very itchy bumps you can go and see a pharmacist for advice on over-the-counter products to stop itching. If the bite becomes more inflamed you should go and see your GP who may prescribe something stronger.
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