In some years whole hordes of red and black patterned insects crawl out of their winter quarters in the ground with the first rays of sunshine and sunbathe together on a stone or a warm spot in the forest, park or garden. Fire bugs are among the conspicuous specimens due to their coloration. Their red shell, which is decorated with black dots, lines or triangles, is characteristic. The little animals are very sociable, often hundreds of them appear together. Many gardeners may ask themselves whether their plants are threatened and what they can do about this plague.
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Over 400 species of fire bugs are native to the world. Of these, only five different species live in Europe. In Germany there are only two. In the vernacular, the animals are also often called fire beetles or French beetles.
The name is somewhat misleading, because fire bugs do not belong to the genus of beetles, but to the bugs. They do not have any biting or chewing tools like the beetles, but only a proboscis through which liquid food can be sucked up. Only a few specimens are able to fly, since the wings are usually poorly developed. The common fire bug is usually about an inch long. Depending on the individual, the coloring can be very different, because the development of the pigment is strongly dependent on the temperature. After hatching from the eggs, the so-called nymphs molt five times during their youth. The black dabs of color develop late. Their final coloring is not reached until adulthood.
The fire bugs use pheromones to call their fellows to gatherings. If danger threatens, alarm scents are emitted and the community dissolves in a matter of seconds.
As soon as the temperatures rise in spring, thousands of fire bugs crawl out of their winter quarters in the ground from mid-March and warm themselves in the first rays of sunshine on stones, house walls or tree trunks. This gets their metabolism going and prepares them for the forthcoming breeding season in April and May. During the mating season, the male fire bugs will be after anything that even remotely glows red and black. Once the right partner has been found, the 30-hour sexual act begins, during which the female lays up to one hundred eggs in various places, simply carrying her partner on her back. For this, the female looks for sheltered places such as under bark, stones or a layer of leaves. After hatching (from May), the nymphs go through six different juvenile stages with different coloring until they finally attain the appearance of the adult fire bug. Only a single generation of fire bugs is produced each year.
Fire bugs have no natural predators. In the event of danger, they secrete a foul-smelling secretion from a kind of defense gland, which usually quickly drives away a potential attacker. On contact with peer enemies, this substance has a paralyzing effect. The secretion is harmless to the significantly larger and superior birds, but makes the bug inedible. Therefore, the bird will henceforth avoid bugs. The red signal color of the shell further promotes this effect. The stench is particularly intense when a fire bug is crushed – a clear warning for the other conspecifics. The bugs are not poisonous. Although the animals can sting, no such cases are known in humans.
What is the danger of fire bugs?
In fact, they pose no threat at all. They do not transmit diseases and do not harm the plants. Therefore, they do not necessarily have to be fought. There are no known cases anywhere in the world where fire bugs have contributed to stunted or even dead plants. Since they do not cause any damage, combating them is never really necessary. Fire bugs are only considered a nuisance, not a pest. Despite this, many people find these animals annoying and extremely uncomfortable. Above all, when they appear in the house or apartment. However, they only do this very rarely and are quickly put back into the wild with a shovel and broom without any odor nuisance.
Fast and effective bug control
If there are whole accumulations of fire bugs in the garden, it is best to push them into a bucket with a broom and release them in another, warm and dry place, far away from your own garden, in the open air. Then the largest number of animals is removed. If you want to combat them effectively, you should never use chemical insecticides. This not only kills the bugs in the garden, but also any beneficial insects like bees and bumblebees. A simple means of killing fire bug nests is easy to make yourself, available in every household and absolutely harmless to other animals, people and nature.
A mixture of:
- Water (rain or tap water)
- Dishwashing liquid (biodegradable)
- alternatively soap solution
A few drops of detergent are mixed with the water in a spray bottle and sprayed onto the bug nests. Very little of the substance is enough, the animals do not have to be drowned. So fogged, the red insects die within minutes.
In short: fire bugs feel at home where it is warm and dry and where they also find enough food. If you don’t want to kill the little animals, you can put the accumulations in a bucket or a sealable container with a shovel and broom and release them again in the wild. Since the bugs appear again and again in optimal living conditions in the garden, these very bases of life should be removed.
As long as there is a rich supply of food for the fire bugs in the garden, there is little point in fighting them. Even the most diligent gardener never catches all the animals, and new bugs are constantly migrating from other areas. Therefore, the best way to get rid of the pesky fire bugs is to deprive them of their food source. Most often the insect can be found only in those places where linden trees grow. Both the fire bug and its nymphs feed mainly on their fruits, the so-called nuts. They drill a small hole into the hard shell with their trunk and secrete a secretion through it that liquefies the core. Then they suck out the liquid. Fire bugs can only eat liquid food, so they can often be seen carrying these nuts around.
- carrion or insect eggs
In rare cases, cannibalism can also be observed. Unlike aphids, fire bugs do not suck the plant juices from the living plant, but essentially limit themselves to the fallen seeds.
It is not necessary to remove all of the growth that fire bugs feed on from the garden. However, it proves to be very helpful to cut off and dispose of the faded infructescence directly (not in the compost). The trees or shrubs produce masses of such small seeds, so that they offer the bugs optimal living conditions. Deprived of their food source in this way, the number of red crawlers quickly decreases, and the population has often shrunk significantly by the second year. But be careful: If the still green seed pods are not cut every year, the unloved bugs will quickly return to the garden.
Fire bugs in autumn
Even with an intensive search, it is never possible to remove all fire bugs from the garden. But if there are only a few specimens there, they will hardly be noticed and usually not perceived as disturbing. When the leaves fall from the trees in autumn, it is also time for the insects to look for their winter quarters. Fire bugs prefer hollow tree trunks, broken pieces of bark, compost heaps or thick layers of leaves in order to gang together in large groups for the winter. If the leaves, dead branches and bark are removed, they have a hard time finding a suitable place. If the leaves are to be left in the garden, at least one check is necessary. The same applies to the compost, especially if it is open (without a cover).
check Anyone who rakes old leaves or cuts back shrubs such as perennials in early spring should keep their eyes on the ground. It is not uncommon for whole clumps of overwintering bugs to be found under broken bark or fallen leaves. These can then be easily collected and set out again in a sunny spot at the edge of the forest. Since the fire bugs hibernate directly at the foot of the host plant, they are primarily found under the floor covering on the trunks of lime trees or mallows.
A particularly clever idea
An American entomologist accidentally discovered a very special way of curbing the spread of the fire bug. He raised firebugs in Petri dishes lined with scraps of newspaper. In some cases he found that the nymphs shed their skin but never reached the adult (adult) bug stage. The discovery was amazing: the scraps of paper that prevented ripening came from an American magazine that made its paper from balsam fir. The wood of this tree prevents the final molt of the larva with a special substance that is similar to the juvenile hormone of the fire bug. The unfinished nymphs can therefore not reproduce and the gardener is left in peace. So whoever has a balsam fir in his garden,
Because of their red color, fire bugs may give the impression of being dangerous. But they are completely harmless to both plants and animals. If you want to get rid of the bugs, which always appear in large groups, you can spray them with a mixture of water and detergent. This leads to a quick death. Nevertheless, sustained control by removing the food source is also necessary, otherwise the little animals will soon return to the garden.