Common Tree Insects & Pests in San Diego

Wood-boring beetles are the most common insects found in North County San Diego. Beetles that bore into tree branches, twigs and trunks include bark beetles, flatheaded borers, and longhorned borers. In addition to wood-boring insects, it is also common to find Aphids, Mealybugs, Psyllids, Scales, and Thrips.

Wood-boring beetles

Beetles that bore into tree branches, twigs and trunks include bark beetles, flatheaded borers, and longhorned borers. In each case, adults lay eggs on or in wood, and larvae feed within the wood, usually making distinctive tunnel patterns called galleries.

A number of different types of insects may bore into tree trunks and branches in their larval stages, producing sawdust or sap-filled holes and weakening trees. Most borers can successfully attack only trees that have been stressed by under- or over-irrigation, disease, lack of proper care, or injury by mechanical equipment. Usually, by the time the tree is infested with borers, there is little you can do to manage them other than improving tree vigor, prune out infected branches, or remove the tree. Insecticides are occasionally used to prevent infestations of bark beetles on high-value trees or to manage certain clearwing moths.

Aphids, Scale & Thrips

These are all small, soft-bodied insects that feed by sucking plant sap. Damage may include leaf stippling, leaf bleaching, leaf curling and distortion, whitish waxy growth, or sticky honeydew (condensed sap) which may support the growth of sooty mold. Although most of these insects are related, thrips are classified in a different group.

Mites

Mites are tiny and difficult to see without a magnifying glass. Mites in the groups listed below may damage fruit trees, vines, berries, vegetables, and ornamental plants. Spider mites cause stippling on leaves. Other pest mites cause a distorted growth of leaves, shoots, buds, or fruit. There are also many carnivorous species of mites that feed on other mites or small insects.

Tree-boring Caterpillars

These caterpillars develop within wood, buds, crowns, or shoots of plants. They may cause a variety of damage symptoms including holes in trunks, weakened branches or crowns, and distorted shoot growth.