The Encyclopedia Americana (1920)/Hay-worm

HAY-WORM, the caterpillar of a medium-sized pyralid moth (Pyralis costalis), injurious to clover hay, and to other hay when mixed with clover. Its depredations can be prevented by keeping the hay dry and well ventilated, as the insect preferably breeds in moist or matted material such as is to be found in the lower parts of stacks; here the hay becomes filled with webbings of the “worms” and their excrement, rendering it unfit for feeding. The webbed material should be burned and the place thoroughly cleaned.