Azaleas often show symptoms of lace bug and spider mite infestations during the hot months of summer. This damage can be prevented by a onetime early application of the systemic insecticide imidacloprid. This insecticide should be poured in liquid form around the root system as the flowers fade, spreading the active ingredients throughout the plant issue where it remains effective through the growing season. Bayer Advanced Tree and Shrub Insect Control is a common brand that contains this safe and effective insecticide. Always follow label directions when applying any pesticide.