Back to Weed-feeders Table of Contents

Oberea erythrocephala
(Coleoptera: Cerambycidae)

by Rich Hansen, USDA-APHIS-PPQ, Forestry Sciences Lab, Montana State University, Bozeman, MT 59717-0278.

Leafy spurge is an Eurasian perennial that was introduced into North America in the 19th century. It infests several million hectares of rangelands and riparian

areas in the United States and is a serious pest across the northern Great Plains where it displaces desirable grasses and forbs normally consumed by foraging cattle. Cattle and horses usually avoid leafy spurge, but should they eat it, its milky latex may cause sickness and even death. Annual direct and indirect economic losses due to leafy spurge infestation in Montana, South Dakota, North Dakota, and Wyoming are estimated to exceed $120 million. In addition, leafy spurge forms monocultures that often displace native plants and degrade wildlife habitats.

Leafy spurge has a number of biological characteristics that have caused it to be difficult to control with herbicides, and infestations generally occur in remote areas consisting of comparatively low-value land. Thus, classical biological control is envisioned as a potentially valuable spurge management tool in North America. To date, ten Eurasian insect species have been released as biocontrol agents of leafy spurge.

Oberea erythrocephala was initially approved for introduction into the United States in 1980. Through 1995, it has been released at leafy spurge-infested sites in at least 15 states across the northern U.S. and in western Canada.

Appearance

Oberea erythrocephala adults are slender beetles 10-12 mm in length, with long, dark antennae. The beetles are slate-gray above with a reddish-orange head, and light grey with reddish markings below; the legs are yellowish-brown. They are active fliers, and may be seen moving above the leafy spurge canopy. The legless larvae are found within leafy spurge roots, and may reach a length of 20 mm. They are white with a yellowish head, and the body is obviously segmented.

Habitat

Leafy spurge-infested grasslands.

Pests attacked

The host range of O. erythrocephala appears restricted to plants in the subgenus Esula of the genus Euphorbia. In Europe, this beetle feeds on leafy spurge and several other closely-related spurge species. There are a few native Euphorbia spp. in the U.S. that could potentially be hosts for O. erythrocephala, though no feeding has yet been documented under field conditions. O. erythrocephala will not feed on poinsettia (Euphorbia pulcherrima), and crop species and native plants outside the genus Euphorbia will not be attacked.

Life cycle

Adult beetles are present in early to mid-summer, and feed on leafy spurge leaves and flowers. After mating, the female beetle chews a hole in the upper part of a leafy spurge stem, into which an egg is deposited. Generally, a single egg is laid per stem, but a female may lay a total of 40 eggs. After hatching, young larvae tunnel down the leafy spurge stem until reaching the root crown area, just below the soil surface. Larvae do most of their feeding within the root crown and larger lateral roots.

Winter is spent in the larval stage, and development resumes in the spring. Larvae construct a cell within the upper root crown in which pupation occurs. Newly-eclosed adults chew through remaining root tissue and emerge from the soil. There is one generation per year in Europe, but it appears that two years may be required to complete the life cycle in the northern U.S.

Relative effectiveness

This species is potentially a valuable biological control agent because of the extensive damage it can cause in leafy spurge root systems. However, there is not yet sufficient information available from North American populations to determine the efficacy of this agent.

Pesticide susceptibility

Not known.

Conservation

For general information about conservation of natural enemies, see Conservation in the Tutorial section on this site, or the Feature Article on conservation in the Midwest Biological Control News.

Commercial availability

Oberea erythrocephala may be available from some state weed management agencies, as well as several commercial suppliers (see the off-site publication, Suppliers of Beneficial Organisms in North America, page of the California Department of Pesticide Regulation website).

Reference

Schroeder, D. (1980) Investigations on Oberea erythrocephala (Schrank) (Col.: Cerambycidae), a possible biocontrol agent of leafy spurge, Euphorbia spp. (Euphorbiaceae) in Canada. Z. angew. Entomol. 90: 237-254.

Back to Weed-feeders Table of Contents