No massive poisonous caterpillar plague likely this year

A Dutch tourist snapped this photo of thousands of oak processionary caterpillars covering a tree at a campsite in Volstroff, France. June 17, 2019
A Dutch tourist snapped this photo of thousands of oak processionary caterpillars covering a tree at a campsite in Volstroff, France. June 17, 2019Photo: NL Times

Fears that the summer of 2020 would be marred by a plague of poisonous caterpillars like last year turned out to be unwarranted. Compared to 2019, there were considerably fewer reports of oak processionary caterpillars causing itching eyes and skin or other problems. In the coming weeks the caterpillars will pupate, which means that issues will decrease even further.

"We are not nearly as busy with the oak processionary caterpillar as last year," Nico Punt of green company Eijkelboom/De Eik Groep confirmed to De Stentor. "We hardly see nests in places where municipalities or provinces have taken measures. If there are any, they are much smaller."

Doctors and health centers also dealt with far fewer patients with itching eyes, throats or skin, Koen Croese of the Knowledge Platform for the  Oak Processionary Caterpillar said to the newspaper. "There are people with complaints, but not nearly as many as last year."

According to Arnold van Vliet, biologist at Wageningen University, there are multiple explanations for this decrease. One is that municipalities and provinces took measures after last year's circus. "Trees were injected with Xentari or treated with nematodes. That appears to be very effective," he said to the newspaper.

The weather also played a role. "In the weeks in which the caterpillars are most active, at the end of June and the first half of July, it was very hot last year. People were walking around with short sleeves and shorts. Because there was also a lot of wind, the conditions were ideal to come into contact with the stinging hairs," Van Vliet said. This summer was a different story, with many rainy days and lower temperatures. 

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