One of the foliage feeding pests Dr. Moorhead discusses at our Forestry Meetings is the redheaded sawfly (Neodiprion lecontei (Fitch)) . It is actually a broadwaisted wasp which feeds on the needles of newly established pine trees. UGA Extension Forester Dr. David Moorhead said environmental conditions are good for sawflies right now.
This morning, we looked at a stand of 2 year old longleaf pines. The larvae of the sawflies chewed the needles back to the fascicle. There are many species of sawflies, and they are very selective in which pine species they feed. They are also treated the same way. They are very susceptible to different insecticides. Their infestations are generally localized, much like an Ips beetle. If the tree is not under stress, it can usually withstand this much damage. Some species have 1 gernation/year while others as much as 3 generations/year.
The redheaded pine sawfly has an olive green body with black stripes or a row of black spots on each side. And a large, black spot on the last body segment. Hosts of this species are loblolly, slash, and longleaf pines. They occur from Virginia to Florida and west to Arkansas and Texas.
Some of our insecticides used do not have a long residual – maybe 2 weeks (depending on rain and sunlight). It is best to treat each tree with active infestations. However, you may see some yellowing within the needles. The female adults have an ovipositor that is serrated which allows them to saw little slits in the needles were eggs are laid. This is how they get the name “sawflies.” Yellowing inside the needles are where females have laid eggs.
For more information visit Conifer Sawflies on the Center for Invasive Species website.