Sawflies are slender wasp-like insects 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 by the presence of a serrated ovipositor at the end of their abdomen, which saws into plant stems to lay eggs, thus the name “sawfly”.
Sawflies feed in the hollow stems of wheat and other cereals, usually above the 1st node below the head. They cause white heads and flagging. Often an emergence hole is in the stem above the node. Sawfly damage can lead to stem breakage or lodging prior to harvest. Montana growers have reported significant economic losses, but this pest has not been particularly problematic in Washington.