European pine sawfly and roseslug are two kinds of sawflies that are currently active. European pine sawfly loves pine, especially mugo, red, and Austrian pines. It has a black head with dark grayish green and light grayish green stripes. They feed on old needles of trees and shrubs and grow as large as one inch long before they are done feeding. While in many cases, defoliation is not severe, they do have the potential to do extensive damage.

Roseslug is a slug-like translucent greenish larva that grows no more than 1/2 inch long. They windowpane feed the leaves of roses. Damaged areas are opaque at first but eventually turn brown. Damage can range from minor to severe.

These sawflies only feed in the spring and are done by June. If they are found on your plants and they are close to full grown size, then feeding is almost complete and treating would do little to protect the plant. If you find them at this stage, your best bet is to just ignore them for this year. If they are less than or equal to half their full grown size they may be worth treating. Treating can be as simple as crushing them with your fingers (wearing vinyl gloves of course). If you are interested in a low impact insecticide, try insecticidal soap or spinosad. You can also use a residual product, such as permethrin or lambda cyhalothrin. Source: Jeffrey Hahn, Extension Entomologist. The full article can be viewed at: http://z.umn.edu/sawflies

If you have questions about sawflies please call me at the University of Minnesota Extension office, Clay County at 218-299-5020, 1-800-299-5020 or email me at nels1657@umn.edu. Check out our website at www.extension.umn.edu/county/clay/