Also known as the westen com root-worm, it is the larva stage of the com root-worm beetle (Diabrotica virgifera virgifera), which historically has laid its eggs on com/maize (Zea mays L.) plants. When they hatch, the larva must feed on the roots of the com/maize plant in order to live. Some strains of Bacillus thuringiensis (B.t.) have proven to be effective against the com root-worm, when sprayed onto them or genetically engineered into the com/maize plant. In the mid- 1 990 ‘s, a new genetic variant (known as the “eastern phenotype”) was discovered in America. It prefers to lay its eggs on soybean plants instead of corn plants.