Branch Borers (Obera schaumii and O. delongi)

From: Ostry, Michael E.; Wilson, Louis F.; McNabb, Harold S., Jr.; Moore, Lincoln M. 1988. A guide to insect, disease, and animal pests of poplars. Agric. Handb. 677. Washington, DC: U.S. Department of Agriculture. 118 p.

Importance- The larvae of these two branch borers attack young Populus stems and branches. Their tunneling breaks infested stems or branches. Heavily infested stems become crooked and forked, reducing commercial value.

Look For: Swollen or crooked stems. Entrance holes with frass protruding from the holes. Yellowish-white larvae ½ to 1 inch long in the pith of the branch or stem. Elongate longhorned beetles that range in color from yellow to black.

Injury to branches and larvae of branch borers Photo by James Solomon, USDA Forest Service

Biology- The adult beetle emerge in April to early July and feeds on the midrib and veins of newly developing leaves. Eggs are deposited in niches gnawed in the bark. Larvae hatch in about 2 weeks and tunnel down the center of the stem. Pupation takes place within the gallery. The life cycle for O. delongi is 1 year; for O. schaumii, 1 to 3 years. O. delongi occurs mainly in the South, while O. schaumii is most prevalent in the North. Woodpeckers often keep these borers in check.

Monitoring- Inspect small-diameter stems and branches for swollen areas and larval tunnels. If 25 percent of stands is infested, consider treatment.

Adult O.delongi feeding on leaf Photo by James Solomon, USDA Forest Service

Control:

• In the nursery, remove and destroy all culled material after harvest.
• In plantations, cut, remove, and destroy infested stems and branches.
• Apply an insecticide recommended for wood borers.