DESCRIPTION
Most forms of spruce gall adelgid are seldom visible. Cone-like galls at the tips of spruce branches is usually the first sign of the pest’s presence.

DAMAGE
Adelgids feed on Colorado, Norway, Alberta, Engelmann and White Spruce as well as Douglas Fir. On Douglas Fir needles turn yellow, become distorted and drop, with black sooty mold often developing, with no galls forming. On spruce 2.5 cm to 5 cm green to purple cone-shaped galls form on branch tips, killing new shoots. Galls later turn brown and remain on the tree for several years.

LIFE CYCLE
Spruce gall adelgid requires both Douglas Fir and Spruce trees to complete its rather complicated life cycle.
On spruce tiny greyish nymphs overwinter on the underside of branches. They mature into adult females in early spring and lay several hundred eggs on branch tips. Eggs hatch just as new growth begins. Nymphs then feed, causing tips to swell into many chambered galls. After about 2 months of feeding galls turn brown, open and nymphs emerge. Nymphs then transform into adult females and fly to Douglas Fir or another spruce to lay eggs.
On Douglas fir females lay eggs in August on the lower surface of current season’s needles. Eggs hatch by September and nymphs settle on underside of needles to overwinter. The following spring nymphs become adult females, lay eggs (enveloped in white fuzz) which give rise to both winged and wingless female adelgids by summer. The wingless form remains to feed on Douglas fir, and lays eggs that hatch into overwintering nymphs. Winged forms fly to spruce where they lay eggs that develop into overwintering nymphs.

CONTROLS
• Apply dormant oil in March, making sure to get good contact on the undersides of branches, to kill overwintering nymphs on both spruce and Douglas fir. Do not use oil on blue spruce.
• Apply pesticides just as new growth opens on spruce and in mid- August on Douglas fir.
• Inspect spruce frequently for galls, and, if practical, hand pick green galls before they open.

PESTICIDES
• Chemical-Diazinon, Latox or Cygon 2E at label rates. Add 5 ml of Safer’s Soap per litre of spray to aid in spreading and sticking.
• Alternative-Safer’s Soap, Trounce, Rotenone or Summer Oil at label rates. Do not use oil on blue spruce. (to print, right-click on this page)