Cooley Spruce Gall Adelgid / Eastern Spruce Gall Adelgid
Scientific Name: Adelges Cooleyi / Adelges abietis
Adelgids are aphid-like insects that suck the sap out of spruce trees. Their sucking initiates a reaction in the tree that creates the galls in which they reside. By the time the galls turn brown, the adelgids have left. Treatment to prevent gall formation must be initiated before the first feeding by the insects in the spring.
Attacks: Colorado spruce, white spruce, Norway spruce, Douglas fir
What you will see:
- Large brown pineapple–like structures at end of twigs
- Large green pineapple-like structures at end of twigs
- Small cotton ball-like egg masses
Life cycle:
- Overwinters as females attached to the current year’s twigs at the bases of buds
- Females mature and lay 150 to 200 olive-green eggs. Eggs hatch into yellow nymphs
- Nymphs move to needle bases to feed and form galls
- Nymphs molt three times in the gall and emerge in August and September
- Mature nymphs crawl to needles and molt into winged females
- Nymphs lay a second generation of eggs (up to 60) then die
- These eggs hatch into the overwintering females
Cultural Management of Spruce Gall Adelgid
Cultural practices:
- Remove and destroy green galls
- This technique is only effective where the trees have few galls
- Plant less susceptible trees (true firs)
Effective chemical treatments include systemic and foliar insecticides. Follow your Consulting Arborist’s recommendations.
An integrated approach
When caring for urban trees it is important to make a complete evaluation of all environmental conditions to accurately diagnose all stress factors and prescribe care based on specific circumstances. This prescriptive care will help your tree meet its full potential.
