Plant Problem Diagnosis Key / Pests
Pine sawflies
Neodiprion sertifer, N. lecontei and others
Caterpillar-like larvae of small wasps that feed in groups on pine needles. European pine sawfly eats last year's needles in spring and rarely kills a tree; redheaded pine sawfly eats new and old needles in early to midsummer, prefers young pines and can strip them.
Signs
- Groups of gray-green larvae with black heads (European) or yellowish larvae with reddish heads (redheaded) on one branch, rearing up together when disturbed.
- Needles chewed down to dry brown straws.
- Whole branches stripped of older needles, with the new shoots left green.
What favors it
Mugo, Scots, red, jack and Japanese pine. European pine sawfly hatches in late April and May; redheaded pine sawfly feeds on young pines in early to midsummer.
Prevention
- Check pines from late April into May for groups of small larvae on last year's needles.
- Look over young pines again in early to midsummer for redheaded pine sawfly.
Crops it shows up on
Evergreens & conifers (pine, spruce, juniper).
Often confused with
Sources
- SawfliesUniversity of Minnesota Extension
- Conifer SawfliesUniversity of New Hampshire Extension
Treatment by crop
Cultural, biological and chemical options in the order to use them, and notes written for each crop.
Identification is free. Treatment is on the Home and Pro plans.
Questions in the key that lead here
- Look the plant over, leaf undersides included. Are insects, mites, slugs, eggs, webbing or droppings on it?
No, only damage or discoloration - Where is the problem?
A tree or shrub - Which part of the tree or shrub shows the problem?
Needles of a pine, spruce, fir, juniper or arborvitae - What is happening to the needles?
Inner or lower needles yellowing, browning or dropping - What do the older needles look like?
Chewed down to brown straws by groups of caterpillar-like larvae
Not a match? Start the key or describe what you see.
More photos
More from university Extension: search Extension pages on pine sawflies, or find a plant diagnostic lab through your state's Extension.
Other pests
- Aphids
- Bagworms
- Bark beetles of pine and spruce
- Broad mites and cyclamen mites
- Caterpillars
- Cicada and twig-cutting damage
- Colorado potato beetle
- Cucumber beetles
- Cutworms
- Elm leaf beetle
- Emerald ash borer
- Flea beetles
- Fungus gnats
- Galls on leaves and twigs
- Hemlock woolly adelgid
- Japanese beetles
- Lace bugs
- Leafminers
- Mealybugs
- Root aphids
- Root-knot nematodes
- Russet mites
- Sapsucker damage
- Scale insects
- Shore flies
- Slugs and snails
- Spider mites
- Spongy moth (gypsy moth)
- Spotted lanternfly
- Squash bugs and stink bugs
- Squash vine borer
- Tent caterpillars and fall webworm
- Thrips
- Whiteflies
- Wood borers