What's eating my stone pine?

Stone Pine (Pinus pinea), grown for pine nuts, is affected by the pine processionary moth, bark beetles on stressed trees, pine cone beetles that destroy seed-bearing cones, and pine seed bugs. In the US and UK, pine needle scale can also build up. The pine processionary moth is the most damaging defoliator across Mediterranean and Southern European range.

Colonies of hairy caterpillars in silk nests defoliate branches in winter–spring; hairs are highly irritating to skin, eyes, and pets — a health hazard as well as a tree pest Pheromone traps to monitor adults; install collar traps on trunks to intercept processionary columns; Btk spray in early autumn targeting small caterpillars; remove and destroy nests only with full protective gear

Larvae bore into developing cones, destroying seeds within; infested cones show resin bleeding and fall prematurely, causing total loss of that cone's pine nuts Collect and destroy fallen cones with exit holes; pyrethroid spray at cone flush can reduce oviposition; maintain tree health with adequate water and nutrition

Adults bore under bark of stressed or drought-weakened trees; galleries in the cambium girdle shoots or kill entire trees; blue-stain fungus spreads via beetles Keep trees vigorous — water stress is the primary trigger; remove and chip infested wood before beetles emerge; pheromone traps to monitor population levels; no spray is effective inside bark

Piercing damage to immature cones causes resin secretion, cone abortion, and empty or shriveled pine nuts; reduces pine nut yields significantly Hand-collect and destroy bugs in small orchards; kaolin clay on cones reduces feeding; no fully effective chemical control registered for food use in most regions