Common name: European pine sawfly
Scientific name: Neodiprion sertifer
Hosts: There are numerous species of sawflies that feed on conifer needles. One of the most common species in the Midwest is the European pine sawfly (Neodiprion sertifer), which attacks a wide range of pine species, including Austrian, Eastern white, Scots, mugo, red, and Japanese red pines.
The sawfly is not a true fly. It is more closely related to ants, wasps, and bees. The common name “sawfly” refers to the adult stage of its life cycle.
The adult sawfly has a saw-like apparatus at the tip of its abdomen, which it uses to slit plant tissue to allow for easy insertion of eggs.
The larvae of sawfly resemble caterpillars, but have six or more pairs of false legs (prolegs) on their abdomen. Caterpillars have five or fewer pairs of prolegs.
Damage
The adult European pine sawfly is less than one-half inch long, resembling a small bee or wasp. It does very little damage to plants. Most damage occurs during the larval stage of development.
The larvae feed on the needles of pine trees. The larvae will be found feeding on last year’s needles. Needles can be partially or entirely chewed. The larvae feed in groups, and when disturbed, will rear up their heads and the end of their abdomens in a defensive posture.
Life Cycle
The European pine sawfly (Neodiprion sertifer) overwinters as eggs inserted into the needles of the current growing season. The following spring, the eggs hatch and young larvae begin feeding on the outer edges of last year’s needles.
The mature larva has a black head and gray-green body with several light and dark green stripes that break up into spots.
In late spring, after larvae mature and finish feeding, they drop to the ground and spin a cocoon in the leaf litter under the host tree.
Pupation occurs in late summer. The adults emerge, mate, and the female deposits more than 100 eggs into the edges of several needles.
There is one generation per year.
Management
Cultural Management
Healthy trees will tolerate light infestations of sawflies. Removing by hand is effective. Wash the larvae from trees with a forceful stream of water.
Chemical Management
Chemical treatments are seldom needed. If insecticide use is warranted, spray only when larvae are small and feeding on the needles.
The pesticide information presented in this publication is current with federal and state regulations. The user is responsible for determining that the intended use is consistent with the label of the product being used. The information given here is for educational purposes only. Reference to commercial products or trade names is made with the understanding that no discrimination is intended and no endorsement made by The Morton Arboretum.
For more information, contact The Morton Arboretum Plant Clinic at 630-719-2424 or plantclinic@mortonarb.org.