Europe
Scotch broom (Cytisus scoparius)
Eggs are tiny, oval, and white. Larvae are green-brown, translucent, and appear somewhat flattened. They can reach 3–4 mm in length. Pupae are contained within white, silky cocoons 4–5 mm long. Adults are small (3–5 mm long) and are seldom seen. They are white with white antennae, feathered wing tips, and have pale gold markings.
Adults lay eggs on young Scotch broom stems when broom has finished flowering. Larvae hatch in late summer and early autumn and tunnel into young shoots to feed. Larvae develop through six instars over several months and overwinter in the stems of Scotch broom. Larvae emerge in early spring and spin cocoons on broom stems or the undersides of broom leaves, where they pupate. New adults emerge in late spring and early summer when broom flowers. There is one generation per year.
Larval mining causes dieback of Scotch broom stems; however, plants often re-sprout new stems below the sites of damage.
Andreas, J.E., M.J. Pitcairn, and P.D. Pratt. 2022. Scotch Broom 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-2022-7-SCOTCH BROOM-A. https://bugwoodcloud.org/resource/files/25363.pdf