Wheat stem sawfly is an economic pest affecting spring wheat and rye although the species also utilizes several species of grasses as a host. Larval feeding within the stem and girdling behaviour cause economic levels of damage in spring wheat and rye. Densities and the number of adult females are assessed during the mating and oviposition period using a sweep-net. Adult wheat stem sawflies emerge in June and males emerge earlier than females. Adult wheat stem sawflies have a habit of resting on stems with heads downward.
Using a sweep-net, count the number of wheat stem sawflies per 10 sweeps but carefully examine the adults to determine sex. Females can be distinguished from males by the presence of a distinct ovipositor used to insert eggs within the stem of a host plant. An average of 2 females per 10 sweeps generates about 12 % cut stems while 4 females per 10 sweeps cause about 23 % cut stems. Prior to harvest, the number of cut stems per square metre is assessed in order to make future management decisions including field crop rotation or wheat cultivar selection. Stems containing sawfly larvae usually develop a reddish-brown band below either the second or third node.
Access the full field monitoring protocol for wheat stem sawfly.