Iowa Insect Information Notes

Clover Hayworm Moth

Clover Hayworm Moth

The clover hayworm moth is a small, attractive moth that is fairly common in the eastern two-thirds of the U.S. Its name comes from the larvae that formerly were a common pest of stored hay. The caterpillars would infest hay stacks, cover the hay with white silk and consume the clover hay leaves causing considerable damage and loss. Damage was most severe when hay stacks were subjected to excess moisture.

Haystacks, of course, have become a thing of the past, but the clover hayworm is still a common insect. The caterpillars apparently can feed on a wide variety of dried plant materials. Household infestations presumably originate in stored plants such as dried flowers, straw or hay wreathes, coarsely-ground spices and other dried plant items. If our old information describing clover hayworm infestations in hay stacks is accurate, there should be webbing over the surface of the infested dried plant materials and the storage area may be damp or humid.

The clover hayworm moths are as distinctive as they are attractive. They have purplish rose colored wings with wide yellow stripes along the outer edge and yellow marks along the front edge of the front wing. The resting behavior of the moths is distinctive with the tip of the abdomen pointed up into the air.

Clover hayworm moths found outdoors are a curiosity of little concern. Occasionally, the moths are found in barns indicating a possible infestation in stored hay that should be investigated.

Household infestations are the most troublesome, and although the moths are harmless, they are annoying, and more importantly, an indication that a dried plant product within the house is infested. See the paragraph above that describes likely items to be infested.

Control will require locating and eliminating infested materials. The storage area that held infested items should be thoroughly vacuum cleaned. Household insecticide sprays can be used to kill adult moths but this will be a temporary control of little benefit.

Updated 07/14/2005 - 1:35pm