For one Insect, pine needles are the preferred menu item
Spring has arrived, and so have the insects. Caterpillars are crawling abound, one with a unique appetite.
Neodiprion spp. is the most common defoliating insect of pine trees. There are 35 species in all that are native to both the U.S. and Canada. The redheaded pine sawfly, Neodiprion lecontei, is a species found in the Florida Panhandle.
Adult sawflies can be as large as 1/3 of an inch in length. The female can be two-thirds larger than the male. Females are mostly black with a reddish-brown head, with occasionally white on the sides of the abdomen.
The ovipositor or tube-like organ used for laying eggs, is saw-like, hence the common name. During the fall, females make slits in pine needles and deposit individual eggs, up to 120 eggs at a time. The eggs are shiny, translucent white. Mature larvae (caterpillars), as seen in figure 1 in yellow-green, emerge in the spring and feast on pine needles. After weeks feasting on needles, the mature larvae drop to the ground. The cocoon is spun in the upper layer of the soil horizon or in the leaf litter. This is called the pupae stage. The cocoon is a reddish-brown, thin walled cylinder. The pupae overwinter, and adults emerge from the cocoon in the spring of the following year.
Mature larvae are attracted to young, open growing pine stands. Hard pine is the preferred host, but cedar and fir are food sources. Neodiprion lecontei is an important defoliator of commercially grown pine, as the preferred feeding conditions for sawfly larvae are enhanced in monocultures of shortleaf, loblolly, and slash pine, all of which are commonly cultivated in the southern United States. Defoliation can kill or slow the growth of pine trees as well as predispose trees to other insects or disease.
Are there control methods? Yes, biological control is a major factor, as natural enemies are numerous. Disease, viruses and predators help regulate population control. For small scale control, physically removing eggs or larvae is key. Again, most infestations will be on younger tree plantings. So, they’ll be in reach. Just be sure to scout your young pines for signs of infestation. Horticultural soaps and oils are effective chemical controls, if needed.
For more information contact the Gulf County Extension Office at 639-3200.
Supporting information for this article can be found in the UF/IFAS Extension EDIS publication, “Redheaded Pine Sawfly Neodiprion lecontei” by Sara DeBerry: https://edis.ifas.ufl.edu/pdffiles/IN/IN88200.pdf
UF/IFAS Extension is an Equal Opportunity Institution.