Salt marsh caterpillars have a wide host range. They may feed upon broad leaf weeds (especially pigweed), vegetable and field crops plus herbaceous perennials such as mallow, Joe-Pye weed, asters and yarrow. Salt marsh caterpillars are very hairy. Young larvae are yellowish white becoming more reddish brown as they grow, as seen in this photo. Often, caterpillars may be found on the edges of outdoor mum fields especially near weedy areas, but they are active dispersers and can move into the greenhouse to feed upon mums. Young larvae skeletonize the foliage but as they grow you may see large holes in the leaves plus the presence of caterpillar droppings (frass). Adults are fairly large white moths with many small black spots. Larvae can be managed with either chemical insecticides labeled for caterpillars or Bacillus thuringiensis when they are young and actively feeding.
