THE ELDER BORER
(Coleoptera: Cerambycidae)

The elder borer, Desmocerus palliatus, is a striking, bluish-purple beetle with a yellow band across the front part of its wing covers. Its head is quite small compared to the body, having antennae which are 1/2-2/3 of the total body length (2 cm or larger). These beetles infest all types of elder, Sambucus spp., causing galls at the base of the stem, tunnelling in and weakening of the canes, or outright death of the plants.

Adults begin to lay eggs in crevices on the bark near the base of the stem when elders are blooming. Creamy-coloured larvae tunnel within the roots, requiring 2 or more years to mature. When nearly mature, the larvae bore upwards into the pithy stems. These tunnels contain coarse, sawdust-like frass which is pushed out through holes in the stems. After pupating in April and May, beetles emerge from the stem and feed on elder foliage.

CONTROL

If elder shrubs are severely infested, it would be best to remove and destroy the roots and aboveground stems before the end of May.

Vigorous shrubs are less likely to be severely injured by these borers. Because elders normally grow in moist soil along ditches and swampy areas, it is important to maintain adequate moisture in the soil throughout the growing season.

For additional controls, consult Ontario Ministry of Agriculture and Food (OMAF) Publication 64, "The Gardener's Handbook" available through your local OMAF office or by ordering through their website.

R.T. Wukasch/W.A. Attwater

PDCF-026 (Revised 97/08/21)