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.
It is recommended that fall applications of Xytect are applied to control this early spring insect due to the possibility of an early spring infestation. If Xytect soil applications were not applied make sure that at least one well timed foliar spray is done as soon as insects are noted. Begin inspecting for branches that have been stripped of needles and larvae in early April. Management of this pest is best when larvae are small.
Consider Mectinite or Xytect 10% as tree injection treatments for trees that cannot be treated with foliar sprays or other systemic options.
Other Treatment Practices
- Larvae can be removed by pruning off infested branches and destroying.
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.
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
- Young larvae start as 1/8” long and grow to 1 inch long at maturity
Photo: Louis-Michel Nageleisen
Departement de la Sant des Forts Bugwood.org
Photo: John A. Weidhass
Virginia Polytechnic Institute and State University, Bugwood.org
Photo: A. Steven Munson
USDA Forest Service, Bugwood.org
Trees At Risk
- Mugo pine (Pinus mugo)
- Scotch pine (Pinus sylvestris)
- Red pine (Pinus resinosa)
- Jack Pine (Pinus banksiana)
- Japanese red pine (Pinus densiflora)
Other lesser hosts:
- Eastern white pine (Pinus strobus)
- Austrian (Pinus nigra)
- Ponderosa (Pinus ponderosa)
- Shortleaf (Pinus echinata)
- Pitch pine (Pinus rigida)
- Eggs hatch in late April to mid-May (78-220 GDD) 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.
Always refer to product label for rates and approved uses. Some images courtesy of forestryimages.org or Wikimedia Commons. Use of the images does not imply endorsement of treatments.