Chrysolina Motschulsky, 1860

This is a very large genus consisting of about 450 described species and a further 250 subspecies included in 65 subgenera of which 23 are monotypic. Most occur in the Palaearctic, Asian and African zones with only 20 species of 8 subgenera in the Nearctic; some of these are Holarctic, 3 have been introduced as biocontrol agents and 2 are adventive introductions. The U.K. fauna includes 19 species, some of which are recent introductions, and it seems likely that more will be recorded. They are among the largest and most striking of our leaf beetles and although some seem to have declined in recent decades there are several common species that should quickly be recorded. The U.K. species are all medium-sized and relatively easily identified; several other genera include similar sized species e.g. Timarcha Samouelle, 1819, Chrysomela Linnaeus, 1758 and Agelastica Dejean, 1836 but these are readily distinguished on morphological characters and, among our limited fauna, on general appearance. The following description will distinguish the genus from other European Chrysomelids. Head broad and not narrowed anteriorly, prognathous with the mandibles pointing obliquely forwards, antennae broadly separated by the frons, never closely approximated, segments 1-6 glabrous and shiny, 7-11 pubescent and dull. The vertex is variously punctured and the clypeus is often impressed. The terminal segment of the maxillary palpi is usually broader, and is at least as long as the penultimate segment, the apex truncate or weakly rounded. Pronotum transverse, the base as broad as or almost as broad as the base of the elytra, the basal margin smooth, not toothed. Often with a sub-lateral impression or series of punctures, the surface variously punctured. The prosternum lacks antennal grooves and the metasternum is longer than the first abdominal ventrite. Elytra broadly elongate, convex with at most only weakly prominent shoulders, epipleura variously reflexed but always distinctly angled under the lateral margin and delimited by a fine border, the inner margin finely pubescent before the apex. Most species are fully winged and capable of flight. The U.K. species occur on various herbaceous plants; several are nocturnal and, while some are very local and rare, may occasionally occur in large numbers.