Rhagonycha fulva is undoubtedly the commonest of the British soldier beetles (family Cantharidae). It is a familar sight in summer, especially on the flowerheads of various umbellifers such as Hogweed (Heracleum sphondylium), Wild Parsnip (Pastinaca sativa) and Wild Carrot (Daucus carota), or in flight between these plants.
It is one of several soldier beetles (mostly in the genus Cantharis) that can be seen on umbellifers. Many are brightly coloured, at least in part, usually orange or combinations of orange and black. Being variable in colour and size, they are regarded as difficult to identify. Rhagonycha fulva is orange but the tips of the elytra (wing-cases) are black. It is typically 7-10 mm in length. Like other soldier beetles it is relatively soft-bodied, the elytra being thin and rather flimsy, which perhaps relates to the fact that it spends much more time in flight than do most beetles.
It is illustrated in many books, though strangely it has no mention in E.F. Linssen's 'Beetles of the British Isles' – long the standard popular guide though now out of print and scarce. For a long time this confused me, as I couldn't understand how this common and distinctive beetle defied identification. It is, however, illustrated and described in the very useful guide by Harde (1984).
Rhagonycha fulva is part of a community of beetles and other insects that can be seen on flowers. Flower Beetles (Malachiidae) and certain Long-horn Beetles (Cerambycidae) (see, e.g., the page on Leptura quadrifasciata) feed on the pollen and/or nectar. Soldier Beetles, however, feed on other small insects that visit the flowers. Various souces suggest that R. fulva may also feed on the nectar, though this may need to be confirmed? Certainly it is common to see that the beetles have captured prey, as shown in the photograph, even if at first sight they do not seem to be very active. The flowerheads no doubt serve also for basking and for meeting mating partners.
|• ||Harde, K.W. (1984). A field guide in colour to beetles, Octopus Books, London.|