Grammoptera ruficornis (Fabricius, 1781)
Widely distributed throughout England and Wales and with a few scattered records from Scotland north to Ayr (Twinn and Harding). A common and in most years abundant species throughout the Watford area including town centre gardens and wasteland. Adults appear during warm days in mid or late April and are one of the few beetles to be found regularly on the flowers of Prunus spinosa. By May they are common and often found in large numbers on Crataegus and Rosa flowers, Umbels (Apiaceae) almost always host them, and in the absence of other flowers they may be found on Ranunculus spp. The adults are abundant during late May and June when they may be swept from flowers or vegetation in many open habitats and may be seen in flight above low herbage in warm weather. Depending on season they remain abundant through July and into August when numbers fall.

Eggs are laid on thin decaying or recently dead branches of a wide variety of trees and shrubs including Crataegus, Hedera, Hibiscus syriacus, Populus, Ilex, Pyrus malus, P.avarparia, Aesculus, Prunus cerasus, Fraxinus, Ulmus, Quercus, Salix, Acer pseudoplatinus, Prunus spinosa, Corylus, Sambucus and Rhamnus. Bily and Mehl record larvae and pupae beneath the bark of Picea abies. Larvae feed beneath the bark and pupation occurs in a cell excavated in the outer xylem or on the inner face of the bark. Pupation occurs in the spring and the life cycle takes one year.

These small longhorns are easily identified in the field with a X10 lens; although the antennae are sometimes very dark, at least the apical segments will be seen to be lighter, usually orange, basally.

6-10mm. Upper surface black, densely punctate and with creamy-yellow pubescence. Head inclined to body but not vertical, densely punctate with pubescence more dense behind eyes, constricted posteriorly behind prominent temples. Eyes elongate-oval, weakly incised by antennal insertions and almost touching clypeus. Antennal segments mostly bicoloured, dark apically. Second segment short but elongate, first segment shorter than third. Labial palpi testaceous, terminal segment darkened towards apex, enlarged and obliquely truncate. Pronotum quadrate or very nearly so, hind angles produced to a point and hind margin strongly sinuate. Sides smooth, without teeth etc., surface convex and densely punctate, as head, without sculpture. Scutellum elongate and pubescent, as pronotum. Elytra elongate (our specimens averaged 16:6), parallel sided or weakly dilated behind middle and weakly truncate apically, often almost round. Punctures larger and sparser than on pronotum, pubescence sparse, oblique to suture. Femora bicoloured although hind femora may be almost entirely black. All tibiae with a pair of well developed apical spurs. Front tibiae testaceous, mid tibiae lighter in part but often obscurely so, hind tibiae dark. Tarsi dark but for basal segment of front tarsi which is usually lighter. Basal segment of mid- and hind tarsi very long. Antennae more robust and shorter in female.

Description from 4 Watford specimens at X10

See also ID Aids Grammoptera