Small grain-Haanchen barley mealybug

Trionymus haancheni

Pest description and crop damage Adult females are small (0.2 inch long), elongate, oval, segmented insects often covered with white, waxy secretions that extend as filaments along the edges of the body. Nymphs resemble small adults. Eggs are laid in cottony sacs usually in the lower part of the plants. Adult males are the only winged instar. All stages occur at the soil surface or under the leaf sheaths surrounding the stems.

Mealybugs harm plants through feeding damage, honeydew accumulation, and possible toxin injection. Mealybug feeding causes yellowing and browning of foliage. Economic damage has been observed in barley and wheat.

Haanchen barley mealybug has only been documented conclusively in California in the 1960s, Idaho since 2003, and Montana and Washington since 2005. It was also recently reported causing damage in barley fields of Alberta in Canada. Many aspects of this insect's biology still need to be understood before an effective management plan can be implemented.

Management-chemical control

Insecticides are not currently registered for control of these pests.