European Pine Sawfly Diagnostic Guide
The European pine sawfly, Neodiprion sertifer, is an introduced pest that was first found in New Jersey in 1925. It has since spread throughout the Eastern U.S and as far west as Minnesota and south to Missouri. The European pine sawfly affects a variety of pine species. The caterpillar-like larval stage of this insect feeds on the old needles of pine trees in early spring, but not the newly developed needles. This does not kill the host plant, but it can cause a “bottle brush” appearance, which can affect the aesthetic value.
Trees at Risk
Pines including mugo pine, scots pine, red pine, jack pine, and Japanese red pine.
Japanese Red Pine
Signs of Damage
- Yellowing of needle clusters which have been skeletonized by young larvae.
- Shoot death or deformation.
- Old foliage is consumed, but new needles develop normally leaving a “bottle brush” appearance.
- Stunted tree growth.
- 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.
- Larvae range from 1/8”–1” long.
- 3 pairs of thorasic legs.
- Larvae have black heads.
- Eggs hatch in late April to mid-May and larvae feed until mid-June.
- By mid-June larvae drop to the ground and spin brown cocoons in the leaf litter at the base of the tree.
- Pupation occurs within the cocoons in mid-August.
- Adults emerge late August through October.
- Females create slits on the edge of the needle and lay eggs by inserting them into the slits.
- Eggs overwinter in slits of the needles where they were laid.
- One to two generations per year.
Fall applications of Xytect™ are the primary recommendation for sawfly, due to the pest’s early spring emergence and feeding. If Xytect™ soil applications were not applied in the fall, an early spring Transtect™ application as the ground thaws will provide control for the current year. Begin inspecting for larvae and branches that have been stripped of needles in early April. Management of this pest is best when larvae are small.
When used preventatively, Xytect™ is extremely effective in controlling small larvae. Foliar applications can also be expected to yield acceptable results, provided applications are timed with relatively small larvae sizes. Once mid-summer is reached and larvae are large, control is more difficult to obtain.
A Diagnostic Guide is designed to help you identify a pest issue and management solutions. Always refer to product label for all rates and approved uses. Some images courtesy forestryimages.org. Use of the images does not imply endorsement of treatments by forestryimages.org