Europe
Common gorse (Ulex europaeus)
Eggs are tiny, round, and largely transparent. First-instar (larval) mites are light in color and have six legs. Second- to fourth-instar (nymphal) mites have eight legs, are brown, and resemble small adults. Adults also have eight legs, are brick red in color, and are up to ½ mm long.
Adults form a colony beneath large amounts of webbing they produce on the terminal branches of gorse. Females lay eggs year-round on infested shoots. Hatching mites complete four immature stages, with larvae and nymphs feeding on plant tissue. Adults feed on stems and spines and live up to four weeks. There are up to six generations per year, and all stages are capable of overwintering.
Large populations of this mite produce extensive amounts of webbing over mite colonies on gorse terminal branches. Larval, nymphal, and adult feeding stunts branch growth and reduces flowering, thus contributing to a reduction in the spread of gorse. Heavily infested plants are killed by the extensive feeding.
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