Another creepy crawler

Another creepy crawler

Posted by Marianne Hoesen on Thursday, September 15, 2011 Under: nature

You really don´t want to bump into these innocent looking little guys! They are pine processionary caterpillars (Thaumetopoea pityocapa) and live in pine trees.

In the adult phase they are a simple and unremarkable, short lived moth which emerge in the summer and fly at night. A single female can then lay up to 300 tiny eggs which she attaches in a mass to a pine needle. Around one month later these eggs hatch into minute caterpillars. These very social caterpillars live in family communities, eat pine needles by night and sleep in a white silky nest on the tip of a pine branch during the day. These nests appear during the winter as white cotton or ‘candyfloss’ like structures. This period of night time eating occurs during the winter months and whilst low temperatures may slow them down.

Between January and April (depending on spring temperatures) they leave the nest in preparation for the next part of their life-cycle. And it is this point when most people and pets come into contact with the caterpillars, sometimes with very painful consequences. The colony follows a leader, nose to tail, in a long procession. searching for soft soil to burrow into.

The best advice is to avoid these creatures at all costs. The caterpillars are covered in tiny barbed hairs which are their defence mechanism. These hairs are often being shed and so can be airborne around infested pine trees, on the branches where they have travelled and also left in the line of the migrating procession.

When humans and our pets come into contact with these hairs, they can cause reactions ranging from mild inflammation and irritation to severe anaphylactic shock. The worst problems occur if you make contact with the caterpillar directly and ingest the hairs, either by picking it up, stepping on it or moving them in some manner. Once on your skin a rash soon forms which can be incredibly itchy. Medical advice should be sought if you are unfortunate enough to experience this. The rash can be painful, very itchy and lasts for as much as three weeks. People even reported temporary blindness.

Moving the caterpillars, their nests, or even the branches that they have walked along, may release these hairs into the air where they can be inhaled or come to rest unnoticed on clothing. The nest material that remains on the tree after the caterpillars have left will still contain the barbed hairs. Even burning infected pine branches should be avoided as the hairs can be lifted into the air and fall anywhere or be inhaled.

Veterinary services have many emergency calls at the time when the caterpillars are migrating to the ground as inquisitive dogs can get too close to the intriguing procession and may pick up the hairs onto their paws, these irritate and so they lick them. Once the hairs are on the lips/tongue it will induce itching, swelling and possibly vomiting. Also, the caterpillars have a bitter-sweet smell which seems to attract dogs. Look out for the symptoms of small white spots in the mouth and on the tongue, excessive drooling and chomping. In some cases partial amputation of the tongue is the only course of action.

Their favoured food tree is Black pine (Pinus nigra) followed by Canary Island pine (Pinus canariensis), Scots Pine (Pinus sylvestris), Maritime Pine (Pinus pinaster), Aleppo Pine (Pinus halepensis) and Stone Pine (Pinus pinea).

Under no circumstances should you try to handle the caterpillars, cut down the nests or try to burn them.

Experiments in America have shown that if the caterpillars are put in a circle nose to tail they will go round and round until they die from lack of food.