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.