Western Europe
Common gorse (Ulex europaeus)
Eggs are round, small, and translucent yellow. Larvae are cream colored with brown head capsules, C-shaped, and can reach 3 mm in length. Pupae are typically 3 mm long and cream colored, becoming dark gray with age. Adults are gray with very long, slightly curved snouts and brownish gray legs. Faint stripes are sometimes apparent on their elytra, and they are typically 2–3 mm long.
In the continental USA, overwintering adults emerge during late winter or early spring, depending on location. Adults feed on gorse flowers and foliage, causing shot-holes in petals, and deposit eggs into young seed pods. Larvae begin hatching in early to late spring and feed on developing seeds. Larvae develop through three instars. Pupation occurs in seed pods, and new adults emerge in late summer. Adults do not chew their way out of the seed pod, instead relying on the plant’s dehiscing mechanism to escape. Seed pods dehisce, or dry out, and burst open at maturity in order to spread their seeds. Adults feed on spines and stems of gorse and then overwinter among gorse foliage. There is one generation per year.
Adults feed on gorse flowers and foliage, which leads to the destruction of stem tissue but without significantly harming the attacked plant. Larval seed feeding may reduce seed output. While this does not kill existing gorse plants, it can help reduce the rate of spread of gorse populations; however, the overall efficacy of this biocontrol agent is questionable due to high seed production and the longevity of viable seeds in the seed bank.
Andreas, J.E., J. Price, and F.S. Grevstad. 2022. Common Gorse 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-2022-12-GORSE-A. https://bugwoodcloud.org/resource/files/25362.pdf