The gizzard of various birds which are addicted to eating hairy caterpillars, e.g.
Cuculus canorus and trogons, is often lined with the broken-off hairs of these caterpillars, which, penetrating the cuticle, assume a regular spiral arrangement, due to the rotatory motion of the muscles of the gizzard.
Besides the aphids, other insects, such as scale insects (Coccidae), caterpillars of blue butterflies (Lycaenidae), and numerous beetles, furnish the ants with nutrient secretions.
The caterpillars of the leopard moth (Zeuzera pyrina) and of the goat moth (Cossus ligniperda) sometimes bore their way into the trunks and destroy the sap channels.
The early stages if the entrance of the caterpillars has been detected, a wire should be pushed into the hole.