Gonioctena olivacea (Forster, 1771)
This is a generally local and uncommon species throughout Europe from Portugal to Greece and north to Denmark, in the UK it is widespread and locally common throughout England, Wales and southern Scotland and there are populations further north in the highlands. Habitats include most places where the hosts occur; moorland, woodland and road margins and wasteland etc. Adults are active from April until late summer or autumn when they enter leaf-litter and tussocks near to host plants to overwinter; they emerge during the first warm days of spring and disperse by flight to nearby hosts where they begin feeding on freshly developing foliage and shoots. The usual host is common broom, Cytisus scoparius (L.) but also other species e.g. C. multiflorus (L’Her.) or C. striatus (Hill.) and cultivars, Genista tinctoria L. and Ulex, and the adults also feed upon other species of Genisteae including various Laburnum and Lupinus. Adults live for two years and oviposit each season over an extended period from May or June before entering a late summer diapause. Mating occurs in late spring and early summer and eggs are laid singly among leaves and stems of the host, they are retained by the female until almost fully developed and so hatch shortly after being laid. Larvae are characteristic pale brown or grey with a darker head, are finely pubescent, have lateral series of tubercles and transverse dorsal folds and lack urogomphi, they may be found by carefully searching as they feed exposed among the foliage; they pass through 4 instars each taking about a month to complete and when fully grown they descend the stems to pupate in a subterranean cell. Pupation occurs from June until late summer and new generation adults appear from July until October, they feed for a while before aestivating or, in late specimens, overwintering in the soil.
3.5-5.5mm. The combination of colour and the form of the tibiae make this species readily identifiable, more especially so as it is rarely found away from the host. Body very convex; entirely pale yellow-brown with various dark marks to the pronotum and elytra. Head narrow and transverse from above with convex eyes and widely-spaced antennal insertions, the antennae variously darkened apically. Pronotum rounded anteriorly and straight across the base, convex and coarsely punctured. Scutellum black, large, triangular and weakly convex at the apex. Elytra pale, usually with the suture and a longitudinal lateral strip darker to black, with coarsely punctured and regular striae complete to the apex. Legs brown, as the body, tibiae broadened towards the apex, each with a large and sharp tooth on the outer margin near the apex, that on the pro-tibiae smaller than the others. Tarsi 5-segmented; basal segments dilated, third segment strongly bilobed and the fourth tiny, generally hidden within the third, terminal segment long and slender. Claws sharply toothed internally.