Integrated Pest Management
Spruce Ips
Adult blue spruce engraver (Joseph Benzel, USDA APHIS ITP, Bugwood.org)
Blue spruce engraver larva (Whitney Cranshaw, Colorado State University, Bugwood.org)
Spruce ips damage (William M. Ciesla, Forest Health Management International, Bugwood.org)
Pest Description
- adults: ~ 1/6 inch; brown to black
- rear end of beetle is concave and surrounded by four prominent spines
- larvae: white grubs with brown head capsule; no legs
Host Plants, Diet & Damage
- blue spruce (mostly); Engelmann spruce
- feed on tree phloem
- produce pitch tubes and sawdust-like frass
- kill trees systematically from the top down
- can introduce fungal pathogens
Biology, Life Cycle & Damaging Life Stage
- overwinter as larvae (mostly) or adults under the bark
- two to three generations per year
- emerge in early spring with warming temperatures (warmer than 50 degrees F)
- males mate with multiple females creating diagnostic gallery pattern
- larvae are the damaging life stage
IPM Recommendations
- Reduce stress and keep trees healthy and damage free.
- Irrigate properly.
- Remove affected material (usually tree tops) and remove from site, or debark.
- Monitor nearby spruce trees for signs of Ips attacks.
- If known populations are nearby, an insecticide (carbamate; pyrethroid) applied to the bark prior to beetle flight can protect trees.
For more information, see our Bark Beetles fact sheet.