Defoliation is most severe on small trees and plants and the webbing can cause alarm, however it should not affect the long term health or vigour of host plants and where possible can be tolerated.
Due to the gregarious nature of these caterpillars if they cannot be tolerated, it is sometimes possible to hand-pick or prune out infested shoots.
- Extensive infestations can be treated with an insecticide. Thorough spray coverage is required if control is to be achieved
- Forceful spraying is needed to penetrate webbing
- The contact pyrethroid insecticides pyrethrum (considered organic e.g. Bug Clear Gun for Fruit & Veg, Ecofective Bug Killer), deltamethrin (e.g. Provanto Ultimate Fruit & Vegetable Bug Killer), lambda-cyhalothrin (e.g. Westland Resolva Bug Killer) may have some effect
- The systemic neonicotinoid insecticide acetamiprid (e.g. Bug Clear Ultra) is also available
- Plants in flower should not be sprayed due to the danger to pollinating insects
- Inclusion of a pesticide product does not indicate a recommendation or endorsement by RHS Gardening Advice. It is a list of products currently available to the home gardener
Pesticides for gardeners (Adobe Acrobat pdf document outlining pesticides available to gardeners)