WHAT ARE BED BUGS?
Bed bugs, (Cimex lectularius), are wingless, oval-bodied insects. Bed bugs typically bite at night, attacking the entire body, especially the face, neck, trunk, and hands. There are currently no known cases of infectious diseases being transmitted to people from bed bug bites. In recent years, there has been a significant increase in reports of bed bugs. Anyone, anywhere can get a bed bug infestation. These small, biting insects multiply quickly and travel easily.
WHAT DOES A BED BUG BITE LOOK LIKE AND WHAT DOES IT FEEL LIKE? Most bed bug bites are painless at first, but they can develop into large, itchy skin sores. Some people have no reaction at all. Most bed bug bites eventually go away without any treatment.
There are about seventy species of blood-sucking bedbugs, but they are mostly external parasites of bats and birds. Only three species, two of which specialize in humans, feed on human blood: Cimex lectularius, widespread in temperate countries, and Cimex hemipterus, tropical.
These species of bedbugs all descend from animals that once lived in caves, in the crevices between rocks, and fed on bat blood. Then we Neolithic humans entered the caves, and we began to pay rent to the bedbugs in terms of blood. When we moved into real homes, we brought them with us as unwanted pets, and they never left our homes, becoming more and more specialized. Aristotle talks about them in his Historia Animalium and Pliny in the Naturalis Historia.
Bedbugs have been found in 3,550-year-old Egyptian tombs at Tell el-Amarna, a sign that man has always shared his bed with these cute little beasts.
Bedbugs have a 7-8 mm long body of reddish brown color completely flattened ventrally-dorsally, unlike fleas which are compressed laterally (in case of doubt it is a good way to distinguish them).
After a good blood meal however the abdomen swells and becomes much more rounded. They belong to the large group of hemiptera and are hemimetabolous, that is the young, called nymph, looks a lot like the adult except for a few details.
After the egg hatches, there are five nymph stages: to move on to the next level you need to have at least one good blood meal and molt the exoskeleton. Adults need a blood meal to mate.
So overall a bedbug needs you a minimum of six times during its life, but if it has you available it is happy to suck you every few days. If it has to, however, a bedbug can survive without eating for 12-18 months, which is not bad because it means that a house abandoned for a year can still present the risk of an infestation.
The reproduction mechanism of these insects is remarkable and deserves mention. In fact, they use a system called “traumatic insemination”: the male’s penis is modified into the shape of a stiletto and instead of introducing it into the female genital tract as happens with most other insects, the male proceeds as follows: he “captures” a receptive female, turns her over and “stabs” her with his penis directly in the abdomen, ejaculating into the abdominal cavity. The spermatozoa will then make their own way through the hemocoel to the ovaries.
The female has evolved a spongy reinforcement in the abdominal area where this usually occurs to minimize the trauma. In this way the male eliminates the problem of female selection and mates every time he has an opportunity. To tell the truth, the male bedbug mates with anything that comes within range, whatever: receptive females, passing males, dead bedbugs, pieces of cork in the shape of a bedbug, female bedbugs of other species, male bedbugs of other species. A maniac.
They nest mainly in the cracks in the walls (a reminder of their existence in a cave), sometimes in the bed frame and in the seams of mattresses: with their flattened body they can get in almost anywhere. The use of suitable mattress covers is very important to contain the spread of the infestation, preventing fleas from colonizing the mattress in fact there will be no need to throw it away and buy a new one.
They are light-shy animals, so they only come out of their shelter when it is dark. To orient themselves and find their blood meal, they are able to perceive both the heat emitted by humans and the CO2 emitted by breathing. If one suddenly turns on a light pointing at an infested mattress where a person is sleeping, one can witness the spectacle of the bedbugs retreating, running rather awkwardly and unlike fleas, they do not jump.
Once the victim has been perceived, the bedbugs climb on it, or drop onto it from the ceiling and start looking for a superficial vein where the skin is thinner, for example on the ankles, between the knuckles, on the face, etc.
If the insect does not find the vein or is disturbed for any reason, it moves a little further by a few mm and starts again. The result is that very often bedbug bites are characterized by marks aligned in groups of three. This is a diagnostic sign of a bedbug infestation, of an infestation of a disgusting beast that bites you.
Bed Bug Bites
The mouthparts of bed bugs, like those of all hemiptera, are highly specialized in order to have a stylet with which to sting. Before starting to feed, however, the insect injects a bit of its saliva which contains substances that serve as an anticoagulant, vasodilator and anaesthetic (nitrophorin), so that the host does not wake up from the pain of the bite, as all blood-sucking animals do. The problem is that these substances can be powerful allergens and after a few days, a week or more generally, red blisters can develop in the area where the bite is bitten which cause unbearable itching.
This does not always happen naturally, it depends on the individual response of the immune system which ranges from anaphylactic shock to absolutely nothing, but the typical response is that of red blisters, with a redder dot in the center, very itchy. It seems that after a while of being bitten continuously the body gets used to it and the allergic reaction tends to decrease, but hopefully by then you will have disinfected the house.
Curiously, a characteristic that is almost unique among blood-sucking arthropods, bedbugs do not carry any disease for humans. Anopheles mosquitoes give us malaria, tiger mosquitoes give us chikungunya, sandflies give us leishmaniasis, ticks give us Lyme disease, fleas give us plague, lice give us typhus, and so on and so forth. Bedbugs horrify us much, much more than mosquitoes, because they invade our intimate and private space like our bed. Sometimes the reactions of the human psyche are strange.
Bedbug infestations, once linked to dirt and a very precarious existence, have suffered a dramatic decline after the discovery of DDT, which was sprinkled on homes, people, fields, etc. It was even believed that in the United States, Cimex lectularius was definitively extinct and even in Europe for many years there were no cases. Unfortunately, this is not the case.
In the last ten years, bedbugs have suddenly reappeared and the number of infestations is constantly increasing despite the general living conditions and hygiene improving more and more. Why? First of all because we stopped using DDT. Unfortunately, however, DDT also has devastating effects on the environment so it was abandoned between the fifties and seventies of the last century, except in rare areas of the third world.
Secondly, today we trade and travel much more. Bedbugs do not live on people, but love to hide in small, dark corners. Buying a wooden statue from the East is certainly a good thing for your home decor, but if the object is relatively old and has not been fumigated properly, it is possible that bedbugs, their nymphs or their eggs are hiding inside and I remember that they survive for a long time without eating. It is suspected that the first bedbugs to return to England after disappearing from Western countries were introduced precisely through the import of wood (the first four cases occurred in 1999).
Travelers, however, in the form of dark and cozy suitcases, seem to be the preferred vehicle of these animals, who in themselves walk very little. In the United States, the number of infested hotels is constantly increasing, to the point that a registry has been set up to inform travelers of the risk of bedbugs in their hotel. The hottest area is New York, followed by Florida and North Carolina.
If you plan to go to the USA, you should probably check not only because it is annoying to come back scratching wildly, but also because there is a considerable risk of bringing home an unwanted souvenir, in your suitcase.
In Charlotte, for example, 25% of the hotels checked were infested with bedbugs. In New York City in 2002 there were only two reported cases of infestation, in 2007 there were 6889 reported. Bedbugs easily move from one apartment to the next by crawling in cracks and crevices between walls, so be wary of your neighbor if he has recently been to North America (even in Canada there has been a 600% increase in cases in recent years). Bedbugs are also reported on the rise in Germany, Spain, Australia.
In Italy there have been several sensational cases, always related to travelers (source). On September 24 and October 7, 2005, bedbugs were found on the Lecce-Bolzano Express and on the Eurocity Nice-Naples night train respectively.
In June 2003, numerous bedbugs were found in the bed of a seven-year-old boy in Pisa, after he continued to have erythematous and itchy papules on his legs, while no bedbugs were found in the bed of his sister who slept in the same room.
The family had recently hosted some Nepalese friends who were visiting Europe, and it is believed that the bedbugs were hidden in their luggage. Also in June 2003, a tourist from the Czech Republic had the unfortunate surprise of finding a bedbug infestation in the bed of the house he had rented with three friends 15 km from Pisa, and the poor boy had to go to the emergency room.
The house was usually rented to tourists and before the Prague group there had been several groups of Germans. The house and the bed were sprayed with insecticide and after ventilation the apartment was rented to other tourists. At the end of July a German tourist was bitten by bedbugs again and showed up very angry at the agency that rented the apartment with a bedbug in a cage. Finally the agency decided to call a specialized company.
How do you know if you have a bed bug infestation? There are several indirect signs. One is obviously finding itchy blisters but, as mentioned above, this does not happen to everyone and sometimes you do not notice the problem. A key sign is finding bed bug droppings, which are black or grayish dots that look like coagulated blood, in the bed.
If placed on a white sheet, moistened and rubbed with a finger they should leave a typical trail. Finding exuviae, the old external cuticle that remains after moulting, is another sign, as are small blood stains on the sheets. A check of the mattress seams for adults or nymphs can also be useful in case of doubt. The eggs are large enough to be visible to the naked eye. Finally, bedbugs emit a particular odor (not always detectable by the human nose), so penetrating that a dog can easily be trained to detect it: in the USA many pest control companies now use the "bedbug dog".
I will not dwell on how to eliminate them, I refer you to a good specialized company or to the purchase of a steam vacuum cleaner (nymphs and adults die at temperatures above 45 degrees).
I will focus in closing on a serious problem, namely the sad evidence that these parasites are acquiring more and more resistance to insecticides, pyrethroids.
And now go ahead and scratch yourself...
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