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last updated: 01 Oct 2015
Diabrotica virgifera virgifera
Western corn rootwormEN
The eggs are deposited in the soil during the summer, and are football-shaped, white, and less than 0.004 inches (0.10 mm) long. Larvae hatch in late May or early June and begin to feed on corn roots. Newly hatched larvae are small, less than .125 inches (3.2 mm) long, white worms. They go through three larval instars, pupate in the soil and emerge as adults in July and August, with one generation per year. Larvae have brown heads and a brown marking on the top of the last abdominal segment, giving them a double-headed appearance. Larvae have three pairs of legs, but these are not usually visible without magnification. After feeding for several weeks, the larvae dig a cell in the soil and molt into the pupal stage. The pupal stage is white and has the basic shape of the adult.EN
Corn rootworms are one of the most economically significant consumers of maize in the United States. The western corn rootworm, D. virgifera virgifera, and the northern corn rootworm, D. barberi, are the most significant rootworm species in Iowa, a major corn-growing area. A third species, the southern corn rootworm, D. undecimpunctata howardi, causes much economic damage in other regions. Corn rootworm larvae can destroy significant acreage of corn if left untreated. In the United States, current estimates show 30 million acres (12×106 ha) of corn, out of 80 million total are infested with corn rootworm. Estimates of economic damage to corn growers from the pest are about $1 billion.EN