Eighty oak processionary nests in one place. The one already gets itchy by thinking about it alone, but that does not apply to Ton Stokwielder. In Loon op Zand he has so -called butterfly filter hotels full of the tickles. Parasites and other insects come to this to feed on those nests. “This way the scourge could solve itself.”
In most places the municipality has the nests of oak processionary caterpillars removed by companies that suck or burn the nests. “If you burn the nests, you also kill the parasites and insects that eat the caterpillars. Those parasites solve part of the problem. But they bring them to the combustion oven,” Ton explains.
Ton does not burn the animals, but he works like this:
- The nests are stored at a quarantine spot, surrounded by water. As a result, the caterpillars cannot leave.
- The parasites lay eggs on the caterpillars. From those eggs come larvae that eat the caterpillars.
- Just before the non -killed caterpillars, they go together with the parasites in so -called ‘butterfly filter hotels’.
- Then the larvae are flying. They can escape from the hotel through the holes.
- The single caterpillar that has remained alive in the nest emerges, as it goes, to Vlinder.
- The butterflies cannot escape from the hotel and therefore die in this way.
The butterflies cannot therefore provide even more oak processionary caterpillars in the following year. And at the same time the flies ensure natural control of the caterpillar.
In the Loon op Zand region, where Ton has been doing this for six years, there is now a parasite in 80 percent of the caterpillars. A fairly effective way of combating. According to him, it is more convenient to use this natural way of combating, because there will be more parasites that eat the caterpillar.
A butterfly filter hotel filled with nests prevents up to one hundred thousand new caterpillars, according to Ton. That hotel works well. “In the regions where we use the butterfly filter hotel and do not bring caterpillars to the combustion oven, there is a much less teasing pressure,” Ton knows.
He has sold the method to ten municipalities in Brabant that now use the invention. There are four hundred metal nest boxes from Ton in the Netherlands and a large part of it is in our province. They often hang high in the tree, and are eventually collected to go into the green butterfly filter hotel in Loon op Zand.
Municipalities are paying for costs
The expertise center for the oak processionary caterpillar finds it an interesting method to maintain nature. Nevertheless, she wonders whether it will be widely picked up by municipalities, because municipalities themselves have to take care of it.
“Many municipalities want to spend as little money as possible on combating nests,” says a spokesperson for the expertise center. “We often see that municipalities only pull the wallet if there is a lot of nuisance from the caterpillar. But they often don’t want to do much preventively.”
