The number of oak processionary caterpillars has tripled in many places in the Netherlands compared to last year, according to an enumeration by the Knowledge Centre at Wageningen University, which monitors the critters. The centre’s phone has been ringing off the hook with people asking how to deal with the caterpillar and the effects it has on your health.

Pesky caterpillars affect health

The pesky caterpillars, which the Knowledge Centre looked for in 20.000 trees in Brabant, Gelderland, Northern Limburg and Amsterdam, can cause serious health issues in both animals and humans. In particular, the stinging hairs, which can be spread far from the caterpillar’s nest and remain active for years, can cause skin rashes, breathing problems and severe allergic reactions, amongst other things. There is even a report of a woman partially losing her sight after one of these stinging hairs found its way into her eye!

If you come into contact with this caterpillar's hairs and develop a rash, it can be treated with an antihistamine cream. However, if you develop anything serious, like difficulty breathing or an allergic reaction, head to your GP or hospital!

The caterpillars crawl in a procession-like way over the bark of oak trees, shedding hairs as they go. According to the research, of the trees that were not preventively sprayed with a pest control substance, 75 percent were infested with the caterpillar. Of those trees infested with the critter, 80 percent had more than one nest per tree. Only a quarter of the trees sprayed in precaution were infested, and the nests in these trees were smaller.

Not a priority

The increase in the population of these oak processionary caterpillars is possibly due to global warming, as the creatures have migrated to cooler spots. A biologist at the Knowledge Centre, Arnold van Vliet, feels that the time has come to deal with the pesky caterpillar at a national level. “This problem is not going away. That has economic consequences, for example, for campsites and businesses in the recreational sector. There is uncertainty when it comes to food safety, as the stinging hairs also end up on crops. However, the ministries and services concerned are yet to make it a priority”.