Adelgids (Adelges cooleyii, A. lariciatus, A strobilobius, Pineus pinifoliae, P. similis) are soft-bodied insects closely related to aphids.
The first generation feeds on the succulent new needles at the branch terminals. The insect injects a hormone during feeding which closely mimics plant hormones responsible for cell division.
The tree responds by forming a gall at these feeding sites. The young adelgids enter this gall and are sheltered inside it through their growth cycle.
Cultural or Non-chemical Controls:
- Hand pick the newly formed green galls off the twigs in June and destroy them.
- A chemical application may be warranted in late May if the entire tree is heavily infested.
For more information on chemicals available for control of these pests, call Agriculture Canada's Pesticides Directorate in Ottawa (toll-free) at 1-800-267-6315. Chemical pesticides may be toxic to humans, animals, birds, fish, and beneficial insects. Follow all label instructions and precautions listed by the manufacturer.