Get Printable PDF Version
European Pine Sawfly

This pest overwinters as eggs inserted into needles.

European pine sawflies only eat the previous year's needles.

The adults emerge in September to mate and lay eggs. The male is black with feathery antennae while the female is orange with slightly serrated antennae.

Species: Neodiprion sertifer (Geoffroy)

Distribution:

This pest was imported form Europe and now can be found from southwestern Ontario through New England and west to Iowa.


Hosts:

Prefers Scotch, red, jack, Japanese red, table, mountain and mugho pines. Will feed on white, Austrian, Ponderosa, shortleaf and pitch pines if these are intermixed with the preferred hosts.


Damage:

The young larvae can only eat the needle surface which causes the needles to turn straw colored and wilt. 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 will survive. Larvae will often migrate to new trees if the needles on their current host have been devoured.


Description and Life Cycle:

Usually only one generation occurs and the winter is spent as an egg inserted into slits along the edge of needles. The eggs hatch in April through mid-May and the larvae feed until mid-July. The caterpillar-like larvae are grayish-green and have a light stripe down the back, and 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. Disturbed larvae raise their heads and tails in a threatening manner. Mature larvae drop to the ground and spin tough, brown cocoons in the doff. Some larvae may pupate on the tree. The adults emerge in late August through September to mate and lay eggs. The female is a reddish-orange color and the male is black with feathery antennae. Both look like robust, slow flying bees. Each female lays six to eight eggs in a single needle and 10 to 12 needles are used.


Control Hints:

Best control is obtained when the larvae are still small, so look for the straw-like needles left behind by the young larvae. Inspections should be made in April and May. Some growers assess the potential population by looking for the needles with eggs after several frosts in the fall. These needles are most commonly on the upper third of the tree and on the northeastern side.

Option 1: Biological Control - Parasites and Predators - Several parasites have been introduced for control of this pest and native birds feed on the larvae. Rodents often eat the pupae in the soil. These agents are usually not adequate in Christmas tree plantations.

Option 2: Cultural Control - Pruning of Colonies - Since the larvae congregate together, they are easily removed by clipping out the infested branches and crushed. This is adequate on small trees not ready for harvest and if the colonies are few in number.

Option 3: Chemical Control - Spot Insecticide Sprays - Many growers keep an aerosol insecticide container or a hand pump sprayer handy for quick spraying of detected colonies in the spring during mowings. This is usually adequate for most operations.

Option 4: Chemical Control - General Insecticide Sprays - This sawfly rarely infests large acreages unless controls have not been used for several seasons. General sprays are warranted if more than 25% of the trees are infested.