Phyllobius vespertinus (Fabricius, 1792)
Now generally accepted as a distinct species but still regarded by some as conspecific with P. pyri (Linnaeus, 1758), a supposed ecological difference is that the present species uses various herbaceous plants as hosts while pyri is restricted to trees and shrubs, but there are many references to vespertinus using woody plants (see here). This may be due to the adults being widely polyphagous but using only herbaceous plants as hosts (a not uncommon habit among weevils and leaf beetles), or that there are regional differences in host plants, or maybe there are regional variations in morphology that confuse the situation. Through much of Europe it is regarded as herbaceous-polyphagous but even so there are convincing references to its using various trees, and even to it causing damage to fruit trees in orchards. The UK situation seems to be pretty clear, i.e. that it uses herbaceous plants as hosts, and for this reason alone we describe the species as such here but it should be understood that the real situation is likely to be less clear-cut. The European distribution is mostly western and central but the species has also been recorded from Ukraine, Iran and as Far East as Siberia, to the north it extends into the UK, Denmark and southern Fennoscandia and while it is widespread in Germany and Southern Poland it is otherwise absent from most of the Baltic countries. To the south it reaches the Mediterranean in France and it occurs in Northern Italy, Romania and Bulgaria. Throughout much of this range it is locally common and sometimes abundant and it is present from lowland to middle mountain latitudes in a wide range of habitats. In the UK it is mostly coastal. It is very local and rare although it tends to be common where it occurs; it is rather sporadic along the eastern coast from Kent to the Scottish border and there are records from Cumbria and the Manchester district. Adults first appear in March and are generally common through May and June although they have a wider season on the continent, from March until October. Typical UK habitats include saltmarshes and damp field margins but in Europe the species is more general, occurring also on wetland margins, grassland, dunes, moorland, floodplains, open deciduous woodland, hedgerows and well-vegetated disturbed areas. Known hosts include a range of herbaceous plants and grasses; in the UK often Sea Wormwood (Artemisia maritima L. Asteraceae)) but more generally various Asteraceae and Rosaceae as well as Ground Elder (Aegopodium podagraria L. Apiaceae) and Meadow vetchling (Lathyrus pratensis L. Fabaceae). Larvae develop in the soil feeding externally on roots, they are active and may move between plants to feed and it is likely that they descend into the soil to overwinter, as is typical of the group. Pupation very probably occurs from late winter, depending on the season, to produce the new spring generation of adults from March.
Phyllobius vespertinus 1
4.7-6.5 mm. One of only two UK members of the subgenus Phyllobius s.str. and very similar to our other species, P. pyri. The following combination of features will distinguish these species: Upper surface densely scaled, those on the elytra elongate, narrow and often denser on alternate interstices, and without erect setae. Femora strongly toothed below, tibiae with a sharp external edge. Rostrum quadrate to slightly elongate with lateral scrobes that appear round apically and that extend back to the eyes. The colour is variable but identical between species, body black with green, grey or bluish scales, scutellum with dense white scales (a good field character), antennae reddish-brown with darker scape and club, femora and tarsi darkened, tibiae pale. There are differences in shape between the species but these are only really useful when comparing specimens against a series; compared with pyri, the present species is overall broader, this may become obvious when comparing the width of the forebody against that of the elytra, the eyes are smaller and more convex and the clypeus is level or slightly raised whereas in pyri it is level or may be slightly depressed. The best distinguishing character is the relative proportions of the elytra; in pyri it is more elongate, about 7:4, and at least 1.5X wider than the pronotum, while in vespertinus it is at least 3:2 and usually less than 1.5X wider than the pronotum. A usually obvious feature is the lateral curvature of the pronotum which is stronger in vespertinus. The best clue to the present species is its occurrence on herbaceous vegetation in coastal or near-coastal situations.