Cantharidae

Soldier beetles (1)

COLEOPTERA > POLYPHAGA > ELATEROIDEA > Cantharidae

The common name of soldier beetles comes from the colour patterns of some of the earliest described species that were associated with the jackets and trousers worn by soldiers at that time. Although the name applies to the family as a whole, some of the Cantharis species are now known as sailor beetles.

There are 41 species of soldier beetle on the British List, separated into three subfamilies, Cantharinae, Malthininae, and Silinae with a single representative. The majority of species occur in areas of long grass or low vegetation, including open grassland, agricultural borders, woodland clearings and scrub; some having more specific requirements, favouring dry or wetter habitats.

They vary in size from around 4-12mm, a couple of species slightly larger, are soft bodied, and typically elongate with more or less parallel sided elytra, which may not completely cover the abdomen. Some species are very similar and although most can be distinguished from colour patterns and specific features, others are variable with different colour forms.

The 24 members of the Cantharinae subfamily and the sole representative of Silinae, Silis ruficollis, are considered as the archetypal soldier beetles in terms of general shape and appearance, and with colour combinations of yellow/orange/red, and/or, black/navy blue. This group includes the more common species, notably Rhagonycha fulva (featured on the next page) and quite a few of the Cantharis species, some of which are featured here.

Cantharis rustica, commonly known as the Rustic Sailor Beetle, is one of the larger (9-13mm) and broader species, with a partially dark orange pronotum and entirely black elytra.

Cantharis livida is a similar size, but is a species that has both a dark and a pale form, so could easily be mistaken except for the small black spot behind the eyes, which is a unique feature of the species. Unfortunately, I've only seen the more common pale form, so obviously I can't show the dark form (var.rufipes) for comparison.

Cantharis flavilabris is another that has two colour variants, a dark form with a sooty black pronotum, and a red pronotum form. The latter often being mistaken for Cantharis nigra except that it has a black, rather than dark orange, scutellum. This species is much smaller at just 5-7mm. Both forms are shown here.

Cantharis nigricans is in the same general 'larger black wing-case species' colour group as Cantharis rustica and the dark form of Cantharis livida, also Cantharis pellucida which I haven't yet found and the far less common Cantharis fusca, but can be easily distinguished by the short-haired greyish elytra. The pronotum can be either plain dark orange or with variable dark markings.

Cantharis cryptica is one of the smaller, 7-9mm, pale species that is extremely similar to Cantharis pallida and can only be distinguished from small details such as the flat hairs on the elytra and colour of the palps.

Whilst updating and splitting this page into two parts, I thought it would be interesting to check the distribution data for the various Cantharis species that I haven't yet seen. The five that I have managed to photograph are all relatively common, so it was no surprise to find that they are all in the top ten most frequently recorded. In fact, the top four were Cantharis rustica, C.nigricans, C.flavilabris and C.cryptica. Cantaharis livida was down in ninth place. From the remainder, I picked out three that I'd like to add to my list, Cantharis rufa, C.decipiens and C.pellucida in addition to the dark form of C.livida.