The Corn Rootworm Pest

Each year, U.S. corn yields are adversely impacted by a number of insect pests. One of the country’s most devastating pests is the corn rootworm family – commonly referred to as “Diabrotica” by entomologistsThere are several types of rootworm including the northern corn rootworm (D. barberi), the western corn rootworm (D. virgifera virgifera) and the Mexican corn rootworm (D. virgifera zeae).

Above: western corn rootworm (D. virgifera virgifera)

The corn rootworm does its damage as a larva – the immature stage of the insect.  After mating in the late summer, adult corn rootworms lay their eggs in the soil, depositing them in cornfields in many regions.  The eggs survive the winter underground and hatch in the spring, when the larvae can feed on the roots of young corn plants in farmers’ fields. Rootworm larvae feed almost exclusively on corn roots. Rootworm larval feeding inhibits the corn plant's ability to take up water and nutrients, decreases its ability to develop and remain upright, and – ultimately – leads to possible yield loss, depending on the damage inflicted on the roots by the feeding pests and the growing conditions.

Above: northern corn rootworm (D. barberi)

The corn rootworm has earned the nickname the “billion-dollar bug.” The U.S. Department of Agriculture (USDA) has previously estimated that the damage caused by the pest and costs associated with controlling it typically total $1 billion annually – including approximately $800 million in yield loss and $200 million in treatment expense.

Above:Mexican corn rootworm

Corn rootworms are widely disbursed throughout U.S. corn growing regions east of the Rocky Mountains. It is estimated that approximately 50 million acres of U.S. corn production faces pressure from corn rootworms.