In Greece, as in other Mediterranean countries, you will see white gossamer balls hanging from pine trees. DO NOT TOUCH either the nests, or any caterpillars that may be around. These are the nests of the caterpillar of the Pine Processionary Moth and can be very dangerous to humans and especially animals.

You may also see long lines of caterpillars following each other as they forage for food. Hence their name!

In late August, the female moth lays her eggs on the pine needles which will provide the food that the caterpillars will need when they hatch. The female can lay up to as many as three hundred eggs which at this stage are really minute and they are all clumped together when she deposits them in a mass on the pine needles on the pine tree.

It takes about a month for the minute caterpillars to hatch but once hatched they eat and grow quite rapidly. The caterpillar goes through five growth stages at the end of each stage it moults its skin to accommodate its new growth. It is not until the caterpillar reaches the stage of it third moult that it begins to build the communal silken nest that you see adorning the pine trees.

The pine tree is their food source and the nest protects them from the cold and wet of the winter months. You will often find more than one of these nests on a pine tree and seeing that there can be several hundred caterpillars in a single nest they can do quite a lot of damage to the tree stripping bare the branches near their nest as they eat the pine needles voraciously.

The caterpillars forage and eat by night and sleep by day, this way they avoid attack from many of the daytime predators such as the birds and certain types of wasp.

The caterpillars of the Pine Processionary Moth are dangerous to both animals and people due to the fine poisonous hairs that cover their body. These hairs are part of the defensive mechanism of these caterpillars and can be fatal to cats and dogs and in some very rare cases also to people, if they are allergic to the poison.

A number of years ago, we were informed of one dog here on Thassos, which sadly died after coming into contact with the caterpillars.