Haines Tree and Spray

Sawfly Pupae

Haines Tree and Spray Service has been on the forefront of dealing with many new pest problems in Whatcom County since it has started operation in 1952. We are working closely with WSU cooperative extension and with WSDA state and local officials for the control of pests. We have confirmed with WSDA Chief Entomologist Eric Lagasa that this is the first sighting of this particular pest in Whatcom County. Thanks to Eric for all of his help in this.

HYG-2555-95

David J. Shetlar

The European pine sawfly, Neodiprion sertifer (Geoffroy), is the most common sawfly found infesting pines in landscapes, ornamental nurseries and Christmas tree plantations. Sawfly larvae look like caterpillars but they are the larvae of primitive wasp-like insects. They are common from southwestern Ontario through New England and west to Iowa. This pest was accidentally introduced from Europe.

Plants Attacked

In the landscape, this pest prefers mugho and table top pines. However it readily attacks Scotch, red, Jack, and Japanese pines. It will rarely feed on white, Austrian, Ponderosa, shortleaf and pitch pines, especially if these are intermixed with the preferred hosts.

Damage

The first instar larvae (the ones hatching from the egg) can only eat the needle surface which causes the needles to turn brown and wilt, appearing straw-like. As the larvae grow, they remain together and feed from the tip of a needle to the base. The larvae feed on older foliage and move from branch to branch as they strip the needles. Trees which are entirely defoliated are severely stunted but since the new growth is rarely attacked, the trees may survive. Larvae will often migrate to new trees if the needles on their current host have been devoured. Heavily infested trees end up with a "bottle brush" effect. That is, all the old needles are missing and only the current year's needles are present.

Description and Life Cycle

Sawfly Adult

Usually only one generation occurs and the winter is spent as an egg inserted into slits along the edge of needles. The eggs hatched in April through mid-May and the larvae may feed until mid-June. The caterpillar-like larvae are grayish-green and have a light stripe down the back, a light stripe along each side followed by a dark green stripe. Full grown larvae are about one inch long. The larvae feed in groups or colonies, often with three or four feeding together on a single needle. Distributed larvae raise their heads and tails in a threatening manner. Mature larvae drop to the ground and spin tough, brown cocoons in the duff. A few larvae may pupate on the tree. The adults emerge in late August through September to mate and lay eggs. Each female lays six to eight eggs in a single needle and 10 to 12 needles are used. These eggs can be located after a hard frost turns the egg laying scar yellow.

Adapted from Ohio State University Extension Fact Sheet.