An employee of a specialist firm uses a vacuum cleaner to remove the caterpillars of an oak silkworm in Osnabrück, Lower Saxony
On each such caterpillar, there are about six hundred thousand small stinging hairs from 0.1 to 0.2 millimeters – in addition to those long ones that are visible to the naked eye. Upon contact or contact with the skin, mucous membranes, eyes or respiratory tract of a person, they can cause various inflammations and even life-threatening reactions – similar to nettle burns, reddening of the skin and severe itching, conjunctivitis, asthma attacks, in rare cases – suffocation and anaphylactic shock.
Moreover, the hairs continue to pose a threat also after the appearance of butterflies – they are carried by the wind from the spider nests remaining on the oak trees. Even with not very strong gusts of wind – within a radius of up to hundreds of meters.
The caterpillars of the oak silkworm feed on the leaves of these trees.
Oak silkworm and climate warming
In Germany, we are talking about the caterpillars of the oak silkworm (German: Eichenprozessionsspinner or Eichen-Prozessionsspinner) – one of the species of marching silkworms, the population of which has been increasing here at a rapid pace for many years in a row. They are now found in all federal states. As noted by the dpa agency, the reason for this is the warming of the earth's climate, which has led to the creation of favorable conditions for their reproduction in the local latitudes – very mild winters combined with warm and dry springs. In addition, the trees themselves, due to repeated droughts, have become easier prey for such pests.
Migrating to new feeding grounds, caterpillars of marching silkworms gather in long columns or processions, which is reflected in the names of these butterflies. There are about a hundred species around the world – oak, pine (they, in particular, are found in Russia), pistachio. The names and types are different, but the problems are similar.
When individual trees or areas are found where the oak marching silkworm has spread, local authorities in Germany mark such places with special signs or fence them off with ribbons – they look like red and white police ribbons, but they repeat the words “Eichenprozessionsspinner”. You need to stay away from such places.
Moth – oak marching silkworm
Hiking silkworms – how to deal with them?
If caterpillars have appeared on trees near schools, residential buildings, in city parks or other crowded places, experts are called in to fight – for example, with special industrial vacuum cleaners. They themselves work in protective clothing. The collected caterpillars are sent to incinerators or buried in the ground.
Young caterpillars can be destroyed before hairs appear using chemicals that block the release of the chitinous cover . In some places, with the help of helicopters, they began to spray a liquid with a special bacteria – Bacillus thuringiensis over the trees. They are safe for humans, but the caterpillars die from them, eating the sprayed oak leaves.
Oak Silkworm Nests can also be destroyed by burning directly on trees. This photo was taken in the summer of 2019 in Berlin.
Natural helpers in the fight against this problem are some species of birds – for example, tits, to attract which birdhouses are hung. They eat caterpillars, but only until the hairs appear. After the onset of this stage, the caterpillars remain only in the diet of the cuckoos. In turn, bats feed on moths of the oak silkworm, which also helps to reduce the population.
What to do and when to seek medical attention
In case of contact, you need to take a shower and wash your hair thoroughly, and wash your clothes in a typewriter. It is recommended to cool inflamed skin areas with compresses. Antiallergic medications, hormonal ointments and topical corticosteroids can help alleviate symptoms. In the event of a severe reaction, seek immediate medical attention.
Author: Maxim Nelyubin