Brachypterus urticae (Fabricius, 1792)
Widely distributed and usually common throughout England and Wales, with scattered records from Scotland. Occurs in a wide variety of habitats; woodland, parkland etc. and even the right kind of town centre garden, being dependant on nettles. Adults and larvae feed on the buds and flowers, often in huge numbers and often in company with B.glaber (Stephens). They are common throughout Watford including, occasionally, the town centre occuring from late April (at least in 2007 when April was unusually hot) in small numbers or as single specimens. By late May, depending on season, they are common. By June when the first flush of umbel flowers has finished they are common on Ranunculus flowers near nettlebeds. They remain abundant until September. During the summer they are found on a wide variety of flowers and may be found among swarms of insects in flight above dense vegetation. Shaking umbels into bags during July and August will invariably produce them.

1.5-1.8mm. Head distinctly punctured, cuticle between punctures smooth and shiny, as pronotom and elytra. Pronotal hind margin straight or nearly so (Brachypterolus) with, compared to B.glaber, longer and more pronounced dorsolateral sinuation. Strongly bordered laterally, weakly or not at all basally. Pronotum and elytra with sparse recumbent silver pubescence. First visible abdominal tergite backwardly produced laterally. Upper surface black, usually with some metallic brassy or greeny reflection. Legs, antennae and palpi pale, red to light brown but legs variously darker. Basal tarsal segments strongly bilobed and usually clear yellow. Claws with basal tooth (X50)(Kateretes).
The only confusion that might occur is with B.glaber (Stephens).

Description from 4 Watford specimens at X40