In reply to Rog Wilko:
If it's the same critters at we see in the Herault, it is Pine Processionary Moth Caterpillars. If you get too close, they eject needles which often cause a severe allergic reaction (worse than the Portland caterpillars). If a dog or cat sniffs/licks them, they will need immediate veterinary care.
Easy to spot as they move around in procession (nose to tail) on trees and on the ground. Their nests are fluffy beige clusters at the end of branches on pine trees (sometimes apple trees too, apparently). They move around from late March to April.
We've cut down a few pine trees in our garden for this reason (we have a dog and a cat).