|True firs||Balsam twig aphid|| - Look for trees with curled last season’s needles.|
- On undamaged shoot, look for silvery,
oval-shaped eggs on underside of twig within 1–2 inches of buds.
- Light green stem mothers feed on undersides of needles, excreting honeydew droplets.
|Colorado blue spruce||Cooley spruce gall adelgid|| - Look for brown, pinecone-like galls from the previous season.|
- Gray-black overwintering nymphs are found at the base of the new season’s buds.
|Douglas-fir||Cooley spruce gall adelgid|| - Look for crooked needles.|
- Black nymphs will be on undersides of needles (may be covering over with white wax).
|Norway spruce||Eastern spruce gall adelgid|| - Look for brown galls at the base of previous year’s growth; needles may be missing beyond gall.|
- The black overwintering nymphs will be found at the base of the new season’s buds.
|Pines, spruces, true firs||Eriophyid mites|| - Look at 20 trees per acre that exhibit a gray or rusty coloring.|
- Tiny, peach-colored eggs are found in clusters or rows at the needle base (underside).
- Pale, oblong adult mites move along the needles.
|Pines||Pales weevil|| - Look for trees showing “flagging,” or browning, of needles at the ends of branches that have shown signs of chewing on stem bark.|
- Pull duff away from base of last year’s stumps to look for adult weevils that are becoming active.
|Douglas-fir||Rhabdocline needle cast|| - Scout trees in areas likely to hold extra moisture such as shaded areas along a woodlot or tight plantings.|
- Examine current season’s needles for orange-rust discoloration.
|Spruces||Rhizosphaera needle cast|| - On the lower half of the tree, look for purple-brown needles with visible black fruiting bodies.|
|Spruces||Spruce needle rust|| - On cloudy days, look for needles with yellow bands containing an orange spot.|
- Focus scouting in low or shaded areas.
|Arborvitae, Douglas-fir, spruces, true firs||Spruce spider mites|| - Look for discolored (brown or yellow) needles.|
- Red eggs are found on the undersides of twigs, needles, and at base of buds.
- Reddish-brown adult mites move along needles and twigs.
- Tap symptomatic branches over a white surface to dislodge eggs or mites.
|Douglas-fir||Swiss needle cast|| - In shady or tightly planted areas, look for trees with needles that are browning from the tip down.|
- On the underside of these needles, rows of tiny, black fruiting bodies will be visible with a hand lens.
- Also look for fruiting bodies on healthy, green needles.
|Douglas-fir, pines, spruces||White pine weevil|| - Set out baited pyramidal traps (see Appendix E for instructions).|
- Check soil temperature daily on unshaded side of a tree in susceptible block.
- Once soil temperatures near 50°F, check traps daily.
- On sunny days, look for sap droplets on tree leaders as feeding evidence.