Europe, Asia, Mediterranean
Rush skeletonweed (Chondrilla juncea)
Eggs are tiny and oval. Larvae are somewhat flattened, 1–2½ mm long, and vary from yellow to pinkish-orange. Adults are very small, usually 1–1½ mm long. They are light brown with long, delicate legs. Female abdomens end in a bulbous enlargement.
Adults emerge in spring, and females deposit 60– 180 eggs in leaves of rush skeletonweed rosettes. Larvae feed on stems and stem leaves, inducing the formation of galls. Leaf galls are circular, 3 mm in diameter, and slightly raised, whereas stem galls are elongated and usually more elevated. Pupation occurs within galls with each larva spinning a silky cocoon around itself prior to pupation. Adults emerge from cocoons and galls using pupal head spines. New eggs are laid in stems and stem leaves. There are four or five generations per year. Complete development from egg to adult can take just under four weeks. Larvae or pupae overwinter on winter rosettes or surrounding soil.
Attacked plant tissue is injured or destroyed, leading to fewer branches and flower heads and fewer viable seeds. This does not kill existing plants, but can help reduce the rate of rush skeletonweed spread.
Milan, J., J. Littlefield, C.B. Randall, and J.E. Andreas. 2022. Rush Skeletonweed Biocontrol Agents: History and Ecology in North America. In: R.L. Winston, Ed. Biological Control of Weeds in North America. North American Invasive Species Management Association, Milwaukee, WI. NAISMA-BCW-2022-13-RUSH SKELETONWEED-A. https://bugwoodcloud.org/resource/files/25241.pdf