Several parts of Europe such as Germany and the Netherlands are fighting a serious infestation of oak processionary caterpillars. The presence of the parading caterpillars has increased due to this year’s mild winter and warm spring. Typically the caterpillars turn into moths towards the end of July, eliminating the problem.
A hairy inconvenience
Germany’s heavily populated western Ruhr region is one of the most affected areas. Several schools and parks have been shut down while specialists attempt to rid the oak trees of the caterpillar’s nests. Firefighters in Louvain, Belgium attacked the nests of these troubling insects in preparation for a rock concert.
Dortmund’s Fredenbaumpark was shut down for nearly a month due to the infestation of almost 500 trees. The park manager, Frank Dartsch, said, “The oak processionary infestation this year is very intensive – much more than last year”.
The caterpillars typically have a length between 2 to 3cm (around 1 inch). They march together high into the trees at night and cause a lot of damage to the oaks as they feed on the leaves. A fully grown caterpillar can have around 700,000 hairs that can be dispersed by the wind.
The small hairs being spread by the wind possess a toxin which can produce eye irritation, skin rashes, coughing, and allergic reactions. The nests are too dangerous to be dealt with by anyone who is unprepared. The hairs have tiny hooks that grip into the skin, making it difficult to counteract the thaumetopoein toxin. Dogs are also susceptible to the hairs, as they tend to sniff about near the trees in parks.
How to fight the problem
Special crews have been equipped with protective gear and have been using firefighter lifts to access the tops of the affected trees, where caterpillar nest have been combated with blowtorches and vacuum cleaners. Cortisone is an anti-inflammatory that can ease some of the unpleasant reactions. The caterpillars have few natural predators other than Calosoma beetles and parasites. Cuckoos and orioles will eat them, but not many other birds will go near them. Some areas in Germany have resorted to eco-friendly pesticides that are applied to the oak trees.