While out for a walk in the beautiful countryside the other day we spotted quite a few of the Processionary caterpillar nests,  and even a few processing in file along the ground. 

These caterpillars are highly poisonous and should be avoided at all costs. Don't touch them or their nests,  or you could end up with an extremely nasty reaction.  And certainly don't let dogs near them as the hairs can be fatal.