Now is the time to act against this garden pest in France
Remove processionary caterpillar cocoons before they hatch in spring
Processionary caterpillar nests can be seen high in tree branches and look like cotton wool balls
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Processionary caterpillars, which are classed as a harmful pest in France, can provoke severe allergic reactions in both humans and pets. Now is the time to destroy them while they are in their cocoons.
The caterpillars are named chenilles processionnaires in French due to their tendency to walk in lines along the ground and were officially categorised as a harmful pest in April 2022.
Their characteristic spiky hairs can cause irritation, inflammation, and rashes, as well as breathing difficulties for some.
They can also be dangerous to pets - for example if a dog eats one from the ground - and have been known to cause necrosis of the tongue or mouth.
These reactions can be fatal if not treated.
There are two main species in France, pine and oak (pin and chêne). They each live in trees of their respective types.
Since they were categorised as a pest, communes and departmental prefectures can issue a decree mandating that homeowners destroy any processionary caterpillars on their property.
Read more: Processionary caterpillars in French forest blamed for sick dogs
Destroy the cocoons in winter
Lines of processionary caterpillars can be observed descending trees or walking along the ground from May to June.
They are in their cocoons, which look like balls of cotton wool and can be seen high in tree branches, during the winter months.
To prevent processionary caterpillars from becoming a problem in spring and summer, start by inspecting your trees to spot these nests.
Remove the cocoons by cutting off infested branches.
This operation must be performed using suitable protective equipment, including masks and gloves, to avoid any contact with the stinging hairs, which can come off and spread in the wind when the caterpillars are disturbed.
Then place the branches with the cocoons directly in a garden waste bin to be mulched or taken to the dump.
Read more: How should garden waste be disposed of in France if bonfires are not allowed?
If the nest is too high up in the tree, it is advisable to call in a professional who can use specialist equipment to prune the affected branches or douse the tree with insecticide. This service typically costs around €50 per tree.
You can also favour a natural alternative by putting up bird boxes nearby to attract blue tits and cuckoos, which eat processionary caterpillars.
Traps are also available that attract the bugs as they descend from infested trees.
These traps, which are fitted around the tree trunk, work by funnelling the caterpillars into a plastic bag or pouch.
What are the symptoms of exposure to processionary caterpillars?
Symptoms of irritation (including in pets) are:
Painful, severely itchy rash within eight hours of skin contact
Conjunctivitis (red, painful, watery eyes) within one to four hours in case of eye contact
Sneezing, sore throat, difficulty swallowing and possibly breathing difficulties if inhaled
Hypersalivation, vomiting and abdominal pain if ingested.
