Oak processionary caterpillar
What is it?
The oak processionary caterpillar is the larva of a moth. This moth lays its eggs mainly in the crowns of oak trees. From April through early May, the caterpillars hatch from the eggs. At first, the caterpillars remain high up in the tree. After several molts, groups of caterpillars gather together. They form large nests on the trunks of oak trees. These nests consist of a dense web of threads, stinging hairs, molted skins, and excrement. From their nests, the caterpillars march in a procession (in a line) at night in search of food.
Health issues
The danger posed by the oak processionary caterpillar lies in its stinging hairs. A fully grown caterpillar has about 700,000 of them! These hairs are invisible to the naked eye. With their barbs, the arrow-shaped stinging hairs easily penetrate the skin, eyes, and airways upon contact.
Contact with stinging hairs can cause symptoms within a few hours, such as (severe) itching, bumps, blisters, redness, and inflammation. The eyes may become red and swollen and/or inflamed. Symptoms resembling a cold may occur: a runny nose, a tickle in the throat, coughing, difficulty swallowing, and shortness of breath. In addition, general symptoms may occur, such as vomiting, dizziness, fever, and general malaise. The nuisance caused by the caterpillar’s stinging hairs usually begins in May and continues through August.
What can you do yourself?
If you are experiencing symptoms, it is important to prevent the stinging hairs from spreading further across your body:
- Remove the skin using adhesive tape. Do this immediately after exposure. Then rinse the skin and eyes with lukewarm water.
- Stinging hairs are not easy to remove from clothing. It is best to wash clothing contaminated with stinging hairs very thoroughly (preferably at 60°C).
The symptoms usually go away on their own within a few days to two weeks. If the itching is severe, anti-itch remedies, such as menthol-based ointments, can provide relief. If the symptoms are more severe, it is advisable to see your doctor.
How can you prevent problems?
- When visiting a nature area where the oak processionary caterpillar is present, be sure to cover your neck, arms, and legs properly. Do not sit on the ground.
- Try to avoid direct contact with caterpillars, (old) stinging hairs, webs, and shed skins as much as possible (this also applies to pets).
- Make sure children are aware of the dangers of the oak processionary caterpillar.
- Avoid roads lined with oak trees that have a lot of processionary caterpillars. Even old nests from last year contain many stinging hairs, which can be blown about by the wind.
Are there oak processionary caterpillars in your garden?
If you have oak trees infested with oak processionary caterpillars in your own yard, do not attempt to control the caterpillars yourself. Instead, hire a professional company or contact us for advice.