Top Ten Tree Problems Lace Bug: Lace bugs target broad-leaf evergreens such as andromeda, azalea, and rhododendron. Early detection is the key to getting rid of an infestation. Look for yellow-silver stippling on the topsides of leaves. Mites: Mites pose a serious threat a wide variety of plants, and can seriously impact the visual appearance of a plant. Mites favor warm, dry climates, and are an extremely serious issue for many homeowners. Tent Caterpillars: Caterpillars can weaken many trees and shrubs, increasing the chance of a secondary infestation. Look for silken, yellow cocoons. Borers: Borers are attracted to unhealthy trees, burrowing in and laying eggs inside the trunk. The best defense against borers it keep your trees healthy and unstressed. Hemlock Woolly Adelgid: One of the most common pests, these insects can cause the death of a tree if left untreated. They leave behind a telltale white wax and target primarily older trees. Scale Insects: These insects target primarily hardwoods and conifers. Some signs of an infestation include abnormal leaf and shoot growth, yellow or red leaves, and branch gouting. Anthracnose Disease: This fungal disease affects deciduous and flowering trees. Look for a spotting of foliage in spring and summer. Winter Injury: Even during mild winters, evergreens can lose moisture and not be able to replenish it. Thus, make sure your evergreens have sufficient soil moisture. Weevil Insects: Weevils are commonly found on flowers and fruits.  Look for notches around the edge of leaves. Aphid Insects: Aphids are small and pearl shaped. An infestation can cause yellow discoloration and defoliation.