Small Grain Insects: Sawflies, and Armyworms, and Aphids, Oh, My….

Bill Cissel, Extension Agent – Integrated Pest Management;

Sawflies and True Armyworms
Sample small grain fields for grass sawflies and true armyworms. A sweep net can be a quick and effective way to initially detect grass sawflies. Once you start finding sawflies, beat two rows of small grain together to dislodge any larvae and examine the inner space between the rows. Sample 5 linear feet of inner row space in ten random locations throughout the field. The threshold for sawflies in wheat and barley is 0.4 larvae per foot of row. True armyworms are active at night and seek refuge at the base of plants, under crop residue, and under weeds during the day. To sample for armyworms, examine 5 linear ft of row in at least 10 locations throughout the field. Also note any head clipping and leaf defoliation. The threshold for armyworms is 1 per ft/row in barley and 2 per ft/row in wheat. Fields with mixed infestations of armyworms and sawflies may require treatment even if worm counts of each pest do not exceed threshold levels.

For information on identification, biology, and management, view our Grass Sawfly and True Armyworm Fact Sheet:

For chemical control options, refer to our Small Grain Insecticide Recommendations below.

Watch out for aphids moving into small grain heads. The warm winter/early spring favored aphid reproduction. The English grain aphid is the only species that will infest small grain heads. Its feeding injury can result in shriveled kernels and reduced test weight. The threshold is 15-25 aphids per head when beneficial insect activity is low. One beneficial insect (lady beetle adults and larvae, syrphid fly maggots, lacewing larvae, damsel bugs, and parasitic wasps) per 50-100 aphids is often sufficient to keep aphid populations in check.

Aphid control in small grains in the spring Fact Sheet:

Small Grain Insecticide Recommendations: