Aphids or plant lice are small, soft-bodied insects with sucking mouthparts. They damage leaves, causing the tips of the damaged leaves to curl and die. Most home gardeners do not realize spider mites are present until damage is severe, because these pests are very small and usually go undetected on the underside of leaves. Mites damage leaves by sucking plant juices and chlorophyll. Damaged leaves lose their green color, turning tan and then brown, and eventually die.
Thrips are one of the most serious pests that attack daylilies.
Thrips damage immature stems and blooms. The damage causes discolored, misshapened flowers and reduces flower bud set. When pest infestations are severe or where large numbers of plants are involved, chemical control may be needed. For recommendations on selection and application of insecticides and miticides, contact the cooperative extension service in your county. Although daylilies can be grown readily from seed, variation in seedling populations is great.