A mini-platoon of soldiers wielding blowtorches will be deployed to the Belgian forests to tackle a plague of hairy caterpillars that are causing allergy outbreaks in humans.

Procession caterpillars, so called for the way they march in lines through forests, are covered in long, toxic hairs which cause dermatitis and respiratory problems and account for up to 80 per cent of doctor visits in the affected area.

The soldiers will spend six weeks in the eastern province of Limburg from Monday, waging a tree-by-tree war on the caterpillars, which cling in groups to trunks and branches.

"In teams of two people, they will go through the forests and burn the little animals off the trees," Belgian military spokeswoman Ingrid Baeck said.

"There have not been enough people to do this and I think we can make the difference."

Previous attempts to rid forests of the caterpillars, which number in the millions thanks to mild weather, have included spraying pesticide using a helicopter and setting hormone traps for the adult moths.