Sometimes the bed bugs you find in your apartment is not at all the common bed bugs that breed wildly, bite people endlessly, and seriously spoil lives. For example, take a look at the parasites that one of my subscribers has found in his home:
At first glance, they are really indistinguishable from common bed bugs, but if you track the movements of these tinies in the video, you will see that they crawl into the apartment from swallow nests hanging on the outside wall of the house:
It could mean that these are swallow bugs, a species of the bed bug family. They really look like common bed bugs – widespread and well known human parasites, but differ from them by the peculiarities of their biology.
Common bed bugs and swallow bugs
Bed bugs family includes approximately 100 different species, and only two of them are obligate human parasites - the common bed bug Cimex lectularius and the tropical bed bug Cimex hemipterus.
The tropical bed bug prefers warm climates, so the main areas of their habitat is near the equator. Nevertheless, there are already documented sightings in central Europe and even in Russia. Here’s an interesting fact - if habitats of Cimex hemipterus and Cimex lectularius overlap, the tropical one seems to be crowding out the common bed bug.
But both Lectularius and Chemipterus are specifically human parasites. They bite animals, including birds, very rarely, only out of desperation, when people are not around.
Therefore, most bed bug species are parasites of animals and do not bite human at all, mostly because they do not intersect with people. More than half of these species are the bat parasites, living in the caves and hardly ever seen by humans.
One of these species is the swallow bug, Oeciacus hirundinis. It dwells mostly in nests of passerine birds and feed on both adult birds laying eggs, and then on growing chicks. When chicks leave the nest, bugs lose their food source and start creep around in search of a new inhabited nest, or another host. Part of these parasites hides in cracks and crevices to wait for the spring, another part gets into houses and finds new hosts there (people and pets). Those bedbugs that stay in nests, wait for spring in hope that the birds will return, or will build a new nest nearby where the insects can easily move to on their own six legs.
Probably, swallow bugs can be brought into nests by birds themselves, when, for example, in spring a Martin checks last year's nest, some hungry bug waits for it, clings to its feather and start sucking its blood, while the bird can fly out and move to another nest, sometimes miles away from the old one. Here, in the new nest, parasite can leave his host and remain in new home. And if the birds settle in this second nest, this bedbug will get a steady source of food and a chance to breed.
Why do swallow bugs leave the birds nests and get into flats and houses?
In some nests swallow bugs can reproduce in great numbers. For example, in study that took place in Turkey the researchers extracted dozens of bedbugs from each infested and already abandoned nest (not to mention that some of the bedbugs had already left to find new hosts).
In nest shown in the video there are so many bed bugs, that some of them leave the nest and try to find another place to live in and breed. Perhaps they take this risk because the growing chicks are stirring the bedding in the nest with their feet more and more, perhaps because it's getting too hot. The thermometer on the wall in the video shows almost 45 degrees Celsius. Although this is the temperature straight on the sunlit wall, and in the shade the air temperature is more likely between 30 and 35 degrees, inside the swallow's nest with a crowd of already feathered chicks it can be about 40-42 degrees (the body temperature of small passerines is about 42 degrees, and the chicks can easily heat their nest to the same temperature). Common bed bugs die at this temperature in minutes, but for swallow bugs it is not deadly, although apparently uncomfortable temperature.
It's worth mentioning that the mid and end of summer seems to be optimal season for the spread of swallow bugs. This video was made in late july where the chicks have grown, bugs are satiated and after several months of breeding overcrowd the nest. No wonder that some of them leave the nest and crawl out to find other nests, or at least to find cracks and crevices outside the nest, where they will spend the winter. And during these wanderings swallow bugs can get into apartments and houses. They are small enough to pass freely through the drainage holes in windows, so if they crawl up to the windows, they'll get into the apartment without problem.
Scientific sources, by the way, confirm that such migration of swallow bugs to human housing is not a rarity, but a systematic fact. A huge number of birds, that are the hosts for these insects, nest near human dwellings, so it is no wonder that these parasites breeds quite often exactly on the walls at a distance of several tens of centimeters from the windows, and climb into the cozy quiet houses when looking for new birds nests, or for a winter shelter.
For example, a study from Slovenia points out that before special searches in 1997, all data on swallow bugs in the country were collected only from its occasional encounters specifically in flats and houses. Then scientists began collecting bird nests and extracting bugs from them; before that, they were regularly encountered only in human dwellings. All in all, though finding a swallow bug in the house is not a rule, it’s not that unusual in general. Due to their flat bodies, they will easily crawl into the gap between mosquito nets and window frames, get through drainage holes in windows, or make their way through small gaps in the nets.
Keep in mind that if you have barn swallows, or sparrows, or swifts breeding on your house, then you can meet their parasites. And these bugs live even in relatively cold climate: they are observed, caught and studied almost all over Europe, except the north of Scandinavia, they are even registered in the Baltic States, Sweden and Denmark. So they are not the kind of tropical heat-loving insects.
By the way
If there are no swallow nests on the house, it does not mean there are no swallow bugs. These parasites settle also in the nests of woodpeckers, wagtails, swifts, sparrows, wheatears, starlings, nightingales and other small birds. In Slovenia, the swallow bugs were even found in the nest of european fat dormouse. Almost on every house there are the nest or several nests, suitable for such bugs.
Do swallow bugs bite people?
Hungry swallow bugs bite people, when birds are not available to them, but they can not breed, feeding exclusively on people or even on cats and dogs.
Their bites on human were described in many articles, some scientists from Japan even illustrated the bug biting a person and the blisters, that remains on the skin after such a bite. Also the description of hemipterosis, a skin reaction to bedbug bites, lists the swallow bugs as the causative agents in addition to the common bedbugs.
Consequently, the bed bugs, that have crept into apartment, may start biting humans in a few weeks, when they get too hungry, and the people will be around. Those that are left somewhere in the cracks of the walls outside the house, or in an empty nest, will accept the lack of food, tighten their belts, and starve until spring. On the contrary, those that end up in the apartment will be quite capable of biting humans.
Pretty interesting, that the swallow bug was not biting the author even after it was put to the skin. Maybe it wasn’t hungry and simply wasn’t going to bite, maybe the circumstances was uncomfortable for the bug - bright light and constant anxiety from a person spoilt his appetite. Perhaps if the same bedbug was found in early spring and put on the hand, it would willingly feed on a human as well.
It’s fair to say, that there will be no severe infestation of swallow bugs in the apartment: even from attics or from such nests, as we saw on the video, the bugs creep out not in very large numbers, and in general only few of them will crawl into apartments. And such a pioneers in human house will not breed and will not constantly bite people as well.
How to get rid of swallow bugs at home?
Swallow bugs can be eliminated with the most common insecticides.
For example, author of these videos did a mini-experiment: he sprayed a simple household insect spray to the table, moistened the cap of a pen in a drop of insecticide and drew a circle around the bug with the liquid. The remedy affected the bug and it was already paralyzed in a few minutes.
Basically, if you get a single bed bug anywhere near your windows, or balcony, the easiest is to smash it with your fingers. But if you are too squeamish to do so, you can spray it with insecticide, and it will die.
Due to the fact that swallow bugs do not breed in apartments, there is no need for any specific measures to eliminate large numbers of them in the house.
Also in order to make sure that in the future these insects will not get into your flat, you have to make sure that there are no bird nests near your apartment. In houses with attics it is necessary to install the grids on attic windows to ensures that pigeons, sparrows and swifts will not fly in there to make their nests. That will prevent you from getting not only swallow bugs, but also bird mites, which can be even more problematic.
Distinctions between common bed bugs and swallow bugs
It is important to determine at first encounter whether the insect is an ordinary bed bug or a swallow bug. If you can simply smash a swallow bug and forget about it, a bed bug that you accidentally encounter is usually one of dozens or even hundreds of parasites that already live in your apartment, reproduce in beds, bite you and your children at night, and in a few months spawn in such numbers that they will turn your life into a living hell.
Although there is no considerable distinctions between these species, it is possible to tell them apart.
First of all, the swallow bug is smaller. Adult swallow bugs are 3.5-4 millimeters long, while adult bed bugs are 5-6 millimeters long.
Secondly, the body of swallow bugs is covered with fairly dense hairs. You can easily see it if not with the naked eye then through a magnifying glass. Common bed bugs almost have no hairs on their bodies.
However the most reliable way to identify the swallow bugs at home for sure is to see them crawling through the windows, and further out the windows, see them on the wall near the birds' nests. Just like our viewer did.
On the contrary, the best way to identify common bed bug is to take the bed linen off the bed, or couch, and inspect it carefully. Swallow bugs do not breed in sofas so you will not find a cluster of different-aged parasites of this species with white eggs and black feces there. And if there are such eggs, feces and bugs of any sizes on a bed, then you can be sure that these are common bed bugs having nothing to do with swallows or other birds. If you found them - call an exterminator. Every week and even every day of delay with elimination will more and more turn your cozy flat to cave with hundreds of little vampires.