Leave these well alone as they sting and cause problems!

The Processionary Pine Caterpillar whose usual habitat is in the warmer regions of southern Europe and North Africa has made an appearance in Brittany.  Known in France as "La chenille du pin" , it also lives in oak trees and has recently moved further north in France and also to parts of England, Holland and Germany. 

The caterpillar has very nasty, irritating hairs, which it uses as a sting defence and which causes a rash.  Inhaling a hair can give problems too, especially for anyone with asthma.  Dogs can be badly affected as the irritating caterpillars hairs, rather like nasty fibre glass strands, can cause great irritation to their mouths and tongues and sometimes this develops into a really serious problem. 

Although they like warm climates, the caterpillars are active in winter, coming out at night time even in sub zero temperatures to forage for food.  They return to their nests at dawn where they stay for the day with the nests absorbing the sun which keeps them warm. 

The caterpillars eventually become moths but whilst in the caterpillar stage they live in nests called "tents" in the trees. In late March, when fully grown, they venture out in a long procession, hence their name.  As many as three hundred caterpillars can form a procession and this is most common in the summer when la chenille de pin looks for ground away from its tree in order to go into a "puperal stage" .

In August it comes out from underground having finally hatched out into a moth. These  moths then fly among the fir and oak trees to mate and lay eggs which eventually hatch out into these  caterpillars which while extremely sociable amongst their own kind are very anti-social to us. 

It is strongly advised to leave them well alone and also avoid their "tents" which will undoubtedly contain the irritating hairs.  The caterpillars will initially make several tents before settling down to their final homes.  They like to be in groups and are very voracious eaters and can strip trees quickly of their needles. 

Fortunately there are some birds that can soon eat up the caterpillars and these include the cou-cou.