COUNCILS across the Costa Blanca are well into their annual routine to treat pine trees full of processionary caterpillar nests.
The pest can kill small dogs and make children sick.
Their eggs are laid inside floss nets on pine trees and have been sighted across the region from the Orihuela Costa in the south to the Marina Baixa in the north.
In early spring, the caterpillars leave their nests and head to the ground to pupate and travel in straight lines.
They have tiny barbed hairs containing a protein called thaumetopoein.
This can cause problems for children if they come into contact with them with unwanted consequences like allergic reactions, foaming at the mouth and vomiting.
Dogs are especially at risk because if they accidentally ingest the caterpillars as the barbed hairs could cause severe damage to the tongue.
If they try to eat or even sniff the caterpillars, they could face amputation of their tongue or nose, or even end up dying.