Worcestershire Record No. 5 Nov 1998 p. 10

A RARE OIL BEETLE MELOE RUGOSUS

Oil beetles are a distinctive shape (but there are some similar families) of various colours including green yellow blue (rugosus is dull black). The elytra (wing cases) in the Meloe genus of 7 or 8 UK species are unusual, as they overlap substantially on the front half and are parted towards the apex, over a bulbous abdomen as shown in drawing from Joy 1932 illustrating another species and Harde 1984.

Jake Poloni sent over a live oil beetle found in his garden in Netherton near Bredon Hill. Identification keys Joy 1932, and Buck 1954, indicated Meloe rugosus Marsham, which is rare RDB3 (Hyman and Parsons 1982) with known post-1970 distribution S Devon, E Kent, S Essex, Berkshire, Oxfordshire, E and W Gloucestershire, and Worcestershire, the latter records by Paul F Whitehead (1991)(Broadway, Bredon Hill, Cotswolds) who confirmed my identification. There is another UK similar species M. mediterraneus Mul. (Whitehead 1992) that is not in either of the keys, and is known in Britain from 19th century October records in S Essex, considered in the extinct category (Hyman and Parsons 1984), although may be an unnoticed resident. A few days after the find in Netherton, David Poloni found a similar beetle in Guiting Power, Cotswolds, in Gloucestershire, but a connection with log movements between the two sites seems unfounded, because Meloe could not remain clinging to logs during chain-sawing and then throwing into a pickup.

Meloe are sufficiently big to probably identify alive, usually 10-40mm, and worth looking out for as they are all rare, endangered, or extinct, except M. violaceus (scarce), and may be present in yet unknown localities of relict populations, left since the opening of Straits of Dover 7000 years ago (Whitehead 1991). Habitat - grassland often sheltered and south facing (requiring grazing or cutting to maintain open conditions). They seek shelter during harsher weather; are usually found in autumn; females ovipositing December in soil. They avoid predators by being toxic, by feeding on highly toxic plants such as yew (Whitehead 1991); when handled they exude toxic red haemolymph (insect blood) from joints as a deterrent, as did my specimen, hence "oil beetle".

Meloe are parasitic: M. rugosus parasitises bees nests (mining bee Andrena, and Anthophora haemorrhoa at the colony at Broadway seem evident hosts observed Paul Whitehead 1991). Eggs are laid dug into soil, this is well known. Apparently after hatching and in warmer conditions, the larvae in this stage (triungulin - about 3 mms long) is very active in low plants, from which they hitch onto bees by gripping the hairs (possibly some unfortunately attach themselves to hairy flies - the larvae apparently reacts to any presented hair); many die during this phase, however the female lays many eggs. (Fowler 1891). Drawing of larva in Cooter 1991

Look out for this distinctive family, capture alive any found, and contact. 

Acknowledgements:

References: