What Are Bed Bugs? How To Kill Bed Bugs

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Main Category: Dermatology
Also Included In: Infectious Diseases / Bacteria / Viruses;  Public Health
Article Date: 20 Jul 2009 - 0:00 PDT

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Bed bugs, known scientifically as Cimex lectularius (Cimicidae) are small wingless insects that feed by hematophagy - exclusively on the blood of warm blooded-animals. As we are warm-blooded animals we are ideal hosts for them. Over millions of years bed bugs have evolved as nest parasites - inhabiting the nests of birds and the roosts of bats. Some of them have learnt to adapt to the human environment and live in our nests, i.e. our homes, and more specifically, our beds. Newborns, called hatchlings or nymphs, are tiny, about the size of a poppy seed, while adults grow to about ¼ of an inch long. Their shape is oval and flattened. Both nymphs, eggs and adults are visible to the naked eye.

They are called bed bugs because of their preferred habitat in human homes: sofas, bed mattresses and other soft furnishings.

Bed bugs are seen as a growing problem within all types of dwellings, including private homes, dormitories, cruise ships, army barracks, and shelters.

When seen close up they may have a white, light tan to a deep brown or burnt orange color. Just after molting most of them are plain white. When they have had their feed a dark red or black blob may be observed within their body. They will instinctively seek shelter in dark cracks and crevices when disturbed.

How dangerous are bed bugs to humans?

Most bed bugs feed on their hosts while they are asleep. The host supplies them with blood in a painless way, never knowing it is happening. While feeding they inject a small amount of saliva into the host's skin. The more they feed on one particular host, say a human, over a period of several weeks, the more sensitized that human becomes to their saliva. Until eventually the host develops a mild to intense allergic response.

People who have become sensitive to bed bug bites - their saliva - have lesions similar to mosquito or flea bites. Most humans will think they have been bitten by some insect, such as a mosquito, and never realize who the true culprit was.

The common bed bug, (Cimex lectularius) has adapted well to human environments. It is generally found in temperate climates. Cimex hemiterus is more common in tropical regions, and has mainly poultry and bats as its host. Leptocimex boueti, found mainly in South America and West Africa feeds chiefly on humans and bats. Haematosiphon inodora, of North America, feeds primarily on poultry.

How do bed bugs feed?

The most active time for a bed bug is about one hour before sunrise - the peak time for feeding. However, they will try to feed at any time of day or night if they are hungry enough, and if the opportunity is there. They prefer nighttime and hate sunlight.

They will reach their host either by crawling straight towards them, or climbing a wall and then across the ceiling until they feel a heat wave - when they jump down onto their host. The bug is attracted to the host by both its warmth and the presence of C0₂ (carbon dioxide).

It pierces the skin of its host with two hollow tubes. One tube injects saliva which contains anesthetics, so that the host feels nothing, and anticoagulants, so that the blood flows out freely. The other tube sucks the blood in.

Feeding takes about five minutes, after which the bug returns to its hiding place. Bites are not noticeable by the host until at least a few minutes or some hours afterwards. Hosts, for example humans, will be aware of a bite after scratching it. Often bites may not be noticeable for several days.

Bed bugs will feed every five to ten days. They can, however, last for several months without feeding. If there is no food around they can become dormant for over a year. A well fed bed bug has a lifespan of about six to nine months.

How do bed bugs reproduce?

Bed bugs reproduce by traumatic insemination, also known as hypodermic insemination. The males have hypodermic genitalia which pierce the females anywhere on their abomen and ejaculate sperm into the body cavity. The sperm diffuse through the insides and reach the ovaries, resulting in fertilization.

The female bed bug lays approximately 5 eggs in one day and about 500 during her lifetime. Eggs are about 1 mm long and are visible to the naked eye. They have a milky-white tinge.

The eggs take about two weeks to hatch. The nymphs (baby bed bugs) start feeding as soon as they hatch, and pass through five molting stages before reaching maturity. During each molting stage they need to feed once. It takes about five weeks to reach maturity at a room-temperature environment.

Bed bugs can only reproduce when they have reached maturity.

How do bed bugs get into your house?

Bed bugs may get into a new home as stowaways when luggage, furniture and bedding is moved into a new home - especially in the case of second-hand furniture. Perhaps we should be careful when purchasing second hand furniture at knock-down prices - a careful visual inspection should result in detecting them, if any are present.

Even vacant and seemingly clean homes may have bed bugs in them - they can survive for many months without any food. They can also move from apartment to apartment through hollows in walls and holes and tubes that wires and pipes go through.

A bat or bird that flies into a home could introduce bed bugs, and some other bugs as well.

How do I know if I have bed bugs in my house?

The biggest sign of bed bugs is people complaining of bites that occurred while they were asleep. If this happens you should examine the bedrooms for bed bugs and signs of bed bug activity. Look carefully into the creases in the bed linen, and seams and tufts of mattresses and box springs for bugs or eggs. The eggs will look like tiny pale poppy seeds.

Signs of bed bug activity may exist beneath loose areas of wallpaper near beds, in the corner of desks and dressers, in laundry, and in drawers.

Look out for dark brown or reddish fecal spots (bed bug droppings, excrement). If an area is very infested you may sense a coriander-like odor. The excrement is a liquid that looks either light brown or black that can either bead up or be absorbed by the material around it.

Dogs can be trained to sniff out live bed bugs or past infestations. A dog's sense of smell is so acute that it can pick up the scent of a single bed bug.

What happens when I get bitten?

When you are bitten a raised red bump of flat welt (also called a papule or a wheal) will appear, often accompanied by very intense itching. The anesthetic contained in the bed bugs saliva causes an allergic reaction which results in the red bumps. They look very similar to mosquito bites, but last a lot longer. Signs and symptoms of bug bites will only affect the surface of the skin.

Bites can sometimes take up to nine days to become visible. Unlike flea bites, bed bug bites do not usually have a red dot in the center.

Bed bugs, like fleas, tend to bite in rows. There are likely to be two or three bites all in a row. This is probably because the bed bug is disturbed while feeding, and then comes back about half an inch further down for its next bite; or perhaps it had been trying to find a good vein, and needed several attempts.

About 50% of people who are bitten show no symptoms at all and do not know it happened. This makes it more difficult to prevent or identify potential infestations. Some individuals, however, may become ill and nauseous. It is possible get skin infections and scars from scratching the bites.

When people know they have an infestation of bed bugs in their house they tend to become alarmed. Research, however, indicates that bed bugs do not transmit disease, even though they do bite and take blood. Infections will occur as a result of scratching, and not from a pathogen passed on from the bug.

Very rarely, some people may have an anaphylactic reaction to bed bug bites. It is possible to have an asthmatic reaction when they shed skin as they grow and die; but cases are very rare.

Treatment of bed bug bites

Most bites resolve within one to two weeks. Treatment focuses on relieving symptoms, and include:

• Applying a topical cream, such as cortisone to relieve itching.
• Avoid scratching as this can cause infection.
• If infection does occur an oral antibiotic may be prescribed.
• If there is a severe allergic reaction oral corticosteroids may be prescribed.
• Antihistamines may also help relieve allergic reactions.

As soon as the symptoms are treated it will be necessary deal with the infestation (see below Controlling infestations of bed bugs)

Do bed bugs transmit disease?

Although they look very much like the kind of insect that would transmit disease, like mosquitoes, there are no records anywhere of disease transmission cause by bed bugs - even from sick host to healthy host.

A study carried out by scientists at the Department of Medicine, University of Mississippi Medical Center, Jackson, USA, that reviewed the available evidence on bed bugs found that while they are highly resistant to various ways of getting rid of them, they seem to be more of a nuisance than a serious health problem, but the possibility that they could one day serve as a vehicle for disease has not been well researched.

Scientists say there may be as many as 40 pathogens that could potentially live inside a bed bug or around its mouth area. However, tests have concluded that bed bugs are highly unlikely to carry disease from host to host.

Researchers have concluded that they are much less hazardous to human health than fleas, or other common insects. Nevertheless, these are well formulated opinions, rather than the results of conclusive studies. Some say hepatitis B or Chagas disease could not be discarded as possibilities if the setting were right.

As mentioned before, the biggest risk for humans comes from secondary bacterial infection, which in this case would be as a result of scratching the skin. Scratching, if it breaks the skin, allows bacteria to penetrate - but the bacteria would not have been from the bed bug.

Although they are not known to carry diseases, bed bugs can affect the quality of life of a person who has been bitten, causing distress, discomfort, embarrassment and unsettled sleep.

Controlling infestations of bed bugs

Since they can hide in so many places, they are not easy to eradicate. Unless you have a lot of time at your disposal, and limitless patience, it is advisable to get a professional in pest control. Experts know where to look for them, as well as how to get rid of them.

You can help the pest control professional by removing excess clutter form your house. If your stuff is strewn about rooms the bed bugs will have many extra places to hide, making inspection and eradication that much more difficult.

Some pest control companies may ask you to move furniture away from walls and mattresses and box springs stood on edge before they come in, while others prefer everything to be left where it is so that they can check before moving them themselves.

If you live in an apartment or a house that adjoins another one, it may be necessary to inspect adjoining dwellings to. Bed bugs can easily disperse throughout a building.

The following procedures are advised:

• Bedding and garments which are prone to infestation need to be bagged and laundered at 120 F minimum, because these items cannot be treated with insecticides. Or....


• Place these items in the clothes drier. Set it to high heat for ten to twenty minutes. "Dry-clean only" clothes may be placed in the drier as long as they are completely dry beforehand and are set at moderate heat (less than 160 F). It is possible to send your stuff off to be dry-cleaned - this will kill the bugs; but you may be passing your problem onto the dry-cleaning establishment. When the dry-cleaners open your bags and sort them the little bugs may get away and infest their new home.


• For things that cannot be treated by washing or placing in the drier, wrap them in plastic and place them outdoors in a very hot and sunny location for at least 24 hours. For best results pack each bag loosely. The aim is for an internal temperature of at least 120 F.


• Freezing may also work, but may take several days. It may be an option during winter months when finding hot and sunny locations may not be possible.


• Do not try to kill them off by ramping up the heating in your house - it won't work. Some pest control companies have special heaters for this.


• Although thorough vacuuming may not catch every single bug and egg, it will help get rid of some of the infestation before treatment with insecticides. When vacuuming make sure you include cracks and crevices. Dislodging eggs is extremely difficult - scraping as you vacuum along infested areas, such as fabric folds of beds and sofas and the perimeter edge of wall-to-wall carpets, is more effective. When you have finished make sure you place the vacuum cleaner contents in a sealed bag.


• You may find it is best to throw some infested items away. A pest control professional will help advise you. Make sure you bag these items carefully before moving them.


• Insecticides are a crucial part of getting rid of bed bugs. Do not use baits for ants and cockroaches, they will not work with bed bugs. A good pest control professional will treat all areas where bugs are found, as well as areas bugs tend to like. Depending on the size of your home and the severity of the infestation, this may take several hours. Follow-up visits may also be necessary.


• If you have recently got rid of bats or birds in and around your home it is possible that the bed bugs that fed on them may have switched to human hosts. Bat and bird nesting sites must be treated too.

Scientists at Ohio State University have determined that combining bed bugs' own chemical signals with a common insect control agent makes that treatment more effective at killing the bugs.

Encasing your bed

You could encase both the mattress and box spring in a proactive cover, as some people do for allergy relief. Some pest control firms sell them, as do a number of retail outlets.

As soon as you have encased it and zipped it shut, any bed bug trapped inside will eventually die - as long as you do not unzip it. Some people keep their new beds encased as it prevents the bugs from getting into the mattress and crevices and makes it easier to keep the surface clean and bug free. It is important to remember that encasements do not stop bed bugs from crawling onto them.

Sources:
Department of Entomology, University of Kentucky College of Agriculture. Harvard School of Public Health. Wikipedia. UK Department of Health.

Written by: Christian Nordqvist
Copyright: Medical News Today
Not to be reproduced without permission of Medical News Today

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