Phyllobius argentatus (Linnaeus, 1758)
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POLYPHAGA Emery, 1886
CURCULIONOIDEA Latreille, 1802
PHYLLOBIINI Schönherr, 1826
Dieletus Reitter, 1916
Native to the Palaearctic region this species is generally common throughout Europe, extending north to the UK and central provinces of Fennoscandia, to the east it extends through Asia Minor and Russia to the far east of Siberia and Japan, in the UK it is common throughout England and Wales and more local and sporadic to the far north of Scotland and in Northern Ireland. Adults are active from April until August although specimens have been recorded much earlier and much later than this, typical habitats are open woodland and wooded parkland, gardens, hedgerows and they often occur on isolated trees on moorland etc. They occur on a range of broadleaf trees, particularly Birch (Betula pendula Roth.) but also commonly on Oak (Quercus L.), Hawthorn (Crataegus monogyna Jacq.), Beech (Fagus sylvatica L.) and various willows (Salix L.), adults feed on the foliage and flowers and have been an occasional minor pest of fruit trees and hazel in orchards, especially in the spring when adults may be abundant and feed voraciously. Following a period of feeding they disperse and begin breeding, this typically occurs in the spring but mating pairs may occur into the summer. Females lay small batches of eggs in the soil from late spring, usually among herbaceous vegetation, and larvae emerge after a week or so. Larvae feed through the summer on roots of various weeds and grasses, they pass through five instars and the last of these will overwinter in the soil and complete its development in the spring although it is likely that some become active during mild winter spells and pupate early as adults have been recorded in February, pupation generally occurs in an earthen cell from March and adults tend to emerge in numbers. Sampling adults is easiest by sweeping or beating likely foliage, especially in open and sunny situations, during mild weather they tend to remain inactive on trunks and branches and can be difficult to dislodge; spring is the best time as they may occur in numbers before they disperse, and beating hawthorn blossom can also be very productive.
3.5-6.0 mm. Typically brighter green or golden green than most of our other green weevils, they can be identified in the field with a lens as the round metallic scales overlaid with fine white pubescence are distinctive. Body black, appendages pale brown, sometimes yellowish, although the femora and sometimes the tibiae are often darker. Head elongate with large prominent eyes and parallel temples that are only slightly wider than the rostrum, vertex weakly convex, the pubescence almost recumbent. Rostrum quadrate with scrobes directed towards the eyes and generally obscured by dense scales. Antennae long and slender, a little longer than the elytra, scape curved and gradually thickened to the apex, second funicular segment longer than the first, third funicular segment less than 2X longer than wide, club narrow and pointed. Pronotum transverse, evenly curved laterally and weakly constricted before the basal and apical margins, surface densely scaled and with fine curved and semi-erect pubescence. Elytra elongate, about 2:1, with broadly-rounded shoulders and slightly dilated towards the apex, surface convex and uneven; raised behind the shoulders and transversely depressed in the basal third, interstices densely scaled but the narrow striae are usually obvious, at least in places, pubescence about as long as the interstices, pointed and semi-erect. All femora strongly toothed, femora and tibiae with metallic scales, tarsi pseudotetramerous.