Oak processionary moth and climate change

Thanks to the warmer weather, the oak processionary moth can survive in the Netherlands, and if conditions are right (a warm and dry spring) it becomes a major pest.

Trends

First recorded in the Netherlands in 1991, but subsequent reports of damaged trees indicate that numbers of the oak processionary moth have soared. 1996 was a particularly bad year for tree damage. Thereafter the population collapsed, because of active control and also the cold weather, but in 2001 the number of sightings of caterpillars rose again.

Origin

This species, which likes warm climates, comes from southern and central Europe and has been able to establish in the Netherlands because the climate has changed. The caterpillars tend to congregate on the sunny south-facing side of the trunks of oaks growing in avenues. They are called processionary caterpillars because they form up in long lines on the tree. If there are many caterpillars, their shed hairs may be dispersed by the wind, irritating the skin, eyes and bronchial tubes of humans.

It is expected that this species will remain in the Netherland, and in warm and dry springs will assume plague proportions.