A small skipper butterfly, Thymelicus sylvestris (family Hesperiidae, order Lepidoptera) on a corn cockle flower (Agrostemma githago). Note the long thin proboscis which it proceeded to insert into the centre of the flower to feed on nectar. In this species the tips of the antennae are orange, while those in the similar Essex skipper (Thymelicus lineola) are black. The large skipper butterfly (Ochlodes sylvanus) is also similar but has a pattern of lighter patches on its wings (as well as being slightly larger).
Photo taken in Reading University grounds, Reading, UK, on 2009-06-26.