Oak Twig Pruner
Anelaphus parallelus Newman


Hanson, T., and E. B. Walker. [n.d.] Field guide to common insect pests of urban trees in the Northeast. Waterbury, VT: Department of Forests, Parks and Recreation.


Coleoptera: Cerambycidae

Hosts: Primarily oaks. A related species causes similar damage to other hardwoods. (See below).

Evidence: Look for leafy twigs and branches that are hollow and severed by an encircling mine beneath the bark. These severed twigs are very visible late in the growing season, either littering the ground beneath infested trees or hanging loosely up in the tree. Splitting open a pruned twig will reveal the white larva with long, lemon yellow hairs and a small black head (a).

a. Larvae of the OAK TWIG PRUNER burrow down the center of a twig. The pruned twig eventually falls to the ground with the larva inside it.

Life Cycle: This species has a two year life cycle. In most areas of the northern states, this species has a single brood, so damage is visible in alternating years. Adults emerge in the spring and deposit eggs in and around the bud clusters near the tips of small twigs and branches. During the first season the larvae do most of their feeding in these terminal shoots before wintering in the center of a larger branch. During the second summer, the larva burrows down the center of the stem towards the base until late summer or fall when it severs the twig by making concentric circular cuts to, but not including, the thin bark. The partially-severed branch breaks easily and falls to the ground with the larva inside it. The larva forms a cell between wads of frass within the twig where it pupates and overwinters.

Management: Heavy infestation may seriously damage a tree, but seldom kills it. Prevent adult emergence by collecting and burning severed twigs during the fall and winter. Natural enemies help control this species. Insecticides are rarely needed.

Similar Species: Anelaphus villosus (Fabricius) (twig pruner). This species has a wide host range covering almost all trees except minimally oak and no ash. It even infests woody shrubs. Its life cycle is nearly identical to A. parallelus, but may cycle in alternate years. As the species not only has a similar life cycle but is very similar in appearance to A. parallelus, the two are often confused.

References:

Johnson, W.T. and Lyon, H.H. 1991. Insects That Feed on Trees and Shrubs. 2nd edition. Cornell University Press. p 20;

Solomon, J.D. 1995. Guide to Insect Borers in North American Boradleaf Trees and Shrubs, Agric. Handbook 706, USDA Forest Service, p 429-431.

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