Of all the injuries committed year after year upon field and garden crops, none are more annoying than those due to the ravages of the various caterpillars known as Cut-worms. These are the larvæof dullcoloured, active moths, belonging for the most part of the three genera, Agrotis, Hadena, and Mamestra, and in North America alone constitute an army of no less than 340 different described species, many of which are, at times, very abundant.