As summer starts kicking into high gear in the United Kingdom, these graceful beauties can be found on the wing. A shocking scarlet, cardinal beetles get their namesake due to their colourful resemblance to the vestments of cardinals (no surprises there). For your strange insect fact of the day, a report from 2000 describes a male P. serraticornis feeding on cantharadin secrections from an oil beetle.
Cardinal beetles are generalist predators, chowing down on a wide variety of small invertebrates. They also occasionally take pollen. Their larvae live within decomposing wood, feeding on fungal hyphae and small invertebrates.
There are a couple species of beetles in the UK which are similar. Two rarer types of cardinal beetle can be found. The Black-headed Cardinal beetle (Pyrochroa coccinea), is slightly larger and is a deeper blood red. Finally, the Scarce Cardinal beetle (Schizotus pectinicornis) has a black head like P. coccinea but is only about half the length. It is rare, with an extremely local distribution.
Nardi, G., Bologna, M.A., 2000. Cantharidin attraction in Pyrochroa (Coleoptera: Pyrochroidae). Entomol. News 111, 74–75.
The Wildlife Trusts., 2015. Red Headed Cardinal Beetle. http://www.wildlifetrusts.org/species/red-headed-cardinal-beetle