Yellow-headed Spruce Sawfly
What is it?
Adults are yellow to reddish-brown wasp-like insects about 10 mm long. The larvae are tiny to begin with, often only 3-4 mm long. Mature larvae are 16-20 mm long and have yellowish-brown heads and shiny olive green bodies with paired greyish-green lines the length of the body. The Yellow-headed Spruce Sawfly attack Engelmann, white, black and blue spruce. Larvae eat most of the foliage/needles. This damage may only appear on sections of the tree, not everywhere.
What can I do?
If you identify Yellow-headed Spruce Sawfly larvae on your tree, there are different methods you can use to help your tree. You can;
- pick them off and dispose of them in a sealed garbage bag.
- prune the tips of the branches where the larvae live and dispose of these cuttings in a sealed garbage bag.
- spray affected areas with a high pressure hose. Small larvae cannot crawl back onto the tree however later stage larvae may be able to crawl back up the tree if they are not disposed of after spraying.