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Cooley Spruce Gall Adelgid - Adelges cooleyi    Colorado State, www.ipmimages.org of Lands, www.ipmimages.org www.ipmimages.org  HOSTS: Spruce, douglas-fir. DESCRIPTION:
On
spruce, distinctive pine-cone-shaped galls develop on new growth.
Greenish-gray aphids, covered with a fine powder of wax, are found
within the chambers of the gall. White, woolly aphids are found on
douglas-fir and spruce buds in the spring. When infestations occur on
developing needles, symptoms may include yellowing and twisting of
needles, and sooty mold from the honeydew that the insects secrete. LIFE
CYCLE: Woolly,
white nymphs overwinter on the lower surface of needles and near buds.
In late spring, large egg masses are laid. Eggs hatch in about 20 days
and nymphs move to twig tips to feed on the new needles. Nymphs are
full grown in mid-summer and produce a generation of new insects that
are both winged and wingless. The wingless form remains on the
douglas-fir for a second generation. The winged forms fly to spruce to
complete their cycle.On spruce, winged adults lay eggs that hatch into nymphs which overwinter at the base of spruce needles. Nymphs resume feeding in the spring and lay eggs on the underside of spruce twigs. These eggs hatch at bud break. As the aphids feed on the needles, a greenish-purple, cone-like gall envelopes them. Aphids crawl out of the cracks in the drying gall and molt to a winged adult stage in late summer. These adults migrate back to douglas-fir. CONTROLS:Mechanical: Pruning out galls is ineffective. Chemical: Neem and/or insecticidal soap aimed at the woolly, white aphid stage on spruce or douglas-fir in the spring. Repeat applications may be required. |
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