Wheat Stem Sawfly

Sawflies are primitive wasp-like insects in the Family Cephidae. The adults are slender and laterally compressed with a shining black abdomen and yellow bands. They range in size from 10mm to 15mm long. Females tend to be larger than males and are easily distinguished from males by the presence of an ovipositor at the end of their abdomen. Their serrated ovipositor saws into plant stems to lay eggs, thus the name “sawfly”. They are stingless.

Wheat stem sawfly, Cephus cinctus Norton (Hymenoptera: Cephidae) feeds the hollow stems of wheat and other cereals, usually above the 1st node below the head and causes white heads and flagging.  Often an emergence hole is in the stem above the node. It has a wide range of grass hosts. Sawflies are distributed across Western North America with individuals collected the United States and Canada. Wheat stem sawfly attacks other hollow stemmed native species of grass, as well a many common exotic species of grass such as: smooth brome grass (Bromus inermis), timothy (Phleum pratense), and quack grass (Agropyron repens). Montana growers lose large amounts of money each year, as currently there is no management control in cereals. Tillage is typically practiced for management. Dr. Wendell Morrell of MSU has detected wheat stem sawfly in Washington for several years, but it had not moved to winter wheat before 2005. In 2006 it is fairly common on spring wheat and reported from winter wheat. MSU has a parasitoid which can and will be released into an insectary of sufficient number of sawfly heads.

This information was adapted from the MSU Wheat Stem Sawfly webpage. For more details visit that page.