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European Pine Sawfly
Need to Know
- European Pine sawfly larvae cluster and eat the old needles from mugho, scots, red pin trees and shrubs.
- This defoliation will not kill the plant but will be unaesthetically pleasing and cause possible stunting.
- Pruning infested branches is a simple control method. For larger infestations application of foliar sprays, insecticidal soaps or registered pyrethroid insecticide.
Description of European pine sawflies
Defoliation of pine trees and shrubs by clusters of European pine sawfly larvae is a common problem in Iowa during the month of May. Larvae of this widespread pest are grayish-green with 2 light stripes and 1 dark stripe on each side of the body. The legs and head are shiny black. Full grown larvae, usually present by Memorial Day weekend, are about 1 inch long.
Damage caused by European pine sawflies
European pine sawfly larvae are gregarious and stay together in a cluster as they feed on the old needles from mugho, Scots and red pine trees and shrubs. Because only old needles are eaten and not the new, emerging growth, defoliated trees are generally not killed. Damage may be aesthetically displeasing, especially in Christmas tree plantations, and growth of the tree may be stunted.
Management of European pine sawflies
Control can be as simple as pruning off and discarding infested branches. Heavier infestations on larger trees may justify foliar sprays of horticultural oil, insecticidal soap or a registered pyrethroid insecticide. Spraying is of greatest benefit when done before the larvae become one-half grown. Late sprays, after larvae are full-grown, are usually not warranted.
Do you live in Iowa and have an insect you would like identified?
The Iowa State University Plant & Insect Diagnostic Clinic will identify your insect, provide information on what it eats, life cycle, and if it is a pest the best ways to manage them. Please see our website for current forms, fees, and instructions on preserving and mailing insects.
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