Biological Control of Leafy Spurge

The weed's natural enemies do not occur in the New World, because of its relatively recent introduction.

To achieve biological control, human beings needed to intervene. Small numbers of beneficial organisms that attack leafy spurge have been released in America in the past with limited success. The critical difference between earlier efforts and the current program coordinated by USDA's Animal and Plant Health Inspection Service is one of scale.

APHIS biological control specialists believe that increasing the numbers of beneficial insects released over an extensive area will do better than the modest introductions of the past. The project depends on a broad, coordinated effort with cooperation from many Federal, State, and industry groups.

To start with, USDA officials already have cleared five species of insects from Europe for release in the United States. Together, these spurge enemies make a good team for fighting leafy spurge because they attack different parts of the plant. Some feed on the leaves. Others attack the shoot tips. Still others feed on the stem, the root crown, and the deep secondary roots. Each attack weakens the plant in a different way, thereby exerting a cumulative stress on the weed.

Scientists in USDA's Agricultural Research Service (ARS) are scouting out and evaluating other biological control agents for distribution in North America. Eventually, they hope that there will be enough spurge enemies in North America to achieve the same level of control enjoyed in Europe.

Stem and Root Boring Beetle

The first of the five introduced insects is a cerambyciid long-horned beetle, Oberea erythrocephala Schrank, which was brought in from Hungary and Italy. Females lay an average of 60 eggs and live between 3 and 8 weeks.