Northern corn rootworm

Description:

They are yellowish-green to green in color, and range in length from 4 to 6 mm long. They are very active, tumbling out of the flowers or corn silk when disturbed. Eggs are laid in September, with nearly all adult beetles killed by the first hard frost. In Canada, there is a single generation per year.A total of 44 species of grass, 12 species of broadleaf weeds, and 15 species of broadleaf crops were screened in the laboratory as possible hosts of the larvae of the western corn rootworm, Diabrotica virgifera LeConte.

Habitat:

Rootworm larvae can complete development only on corn and a few other species of grasses. Studies have shown that rootworm larvae reared on other grasses (specifically, yellow foxtail) emerged as adults later and had smaller head capsule size as adults than larvae reared on corn (Ellsbury). Western corn rootworm adults feed primarily on corn silk, pollen, and kernels on exposed ear tips, although they also will feed on leaves and pollen of other plants. If western corn rootworm adults begin emerging before corn reproductive tissues are present, adults may feed on leaf tissue, scraping away the green surface tissue and leaving a window-pane appearance. However, adults quickly shift to preferred green silks and pollen when they become available. Northern corn rootworm adults also feed on reproductive tissues of the corn plant, but rarely feed on corn leaves. Northern corn rootworm adults are more likely than western corn rootworm adults to abandon corn and seek pollen or flowers of other plants as corn matures (Wright).

Notes:

Corn rootworm larvae can destroy significant percentages of corn if left untreated. In the United States, current estimates show that 30 million acres (120,000 km²) of corn (out of 80 million grown) are infested with corn rootworms and area is expected to grow over the next 20 years. The United States Department of Agriculture estimates that corn rootworms cause $1 billion in lost revenue each year, which includes $800 million in yield loss and $200 million in cost of treatment for corn growers (The Dow Chemical Company).