Hylastinus obscurus
Pest description and crop damage Adult beetles are about 0.1 inch long and dark brown. Larvae are creamy white and burrow within the roots of red clover. This insect is primarily a pest of red clover and is the major limiting factor in red clover production west of the Cascades. Because of reduced crop vigor, usually no more than two seed crops are economically feasible.
Management-cultural control
Plowing out and rotation with a cereal crop destroys root borers in the field. However, reinvasion is rapid when red clover is replanted.
Management-chemical control
No labeled insecticides are effective.