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Pyrochroidae – Cardinal Beetles

A family of just three species:

Common or Red-headed Cardinal Beetle Pyrochroa serraticornis
Black-headed Cardinal Beetle Pyrochroa coccinea
Scarce Cardinal Beetle Schizotus pectinicornis

The adults are spectacular large black-and-red beetles.

Common or Red-headed Cardinal Beetle Pyrochroa serraticornis

Black-headed Cardinal Beetle Pyrochroa coccinea. As well as the black head and scutellum, note the more crimson colour of the pronotum and elytra, compared to the more orange-red colour of serraticornis.

Schizotus pectinicornis is smaller (7 – 9 mm; compared to 12 – 19 mm for the Pyrochroa species) and as well as having a black head and scutellum, has a blackish spot in the middle of the pronotum (photo here). A key to the three species is provided in Buck’s (1954) RES Handbook.

All three are saproxylic species with long, flattened larvae that develop under bark of decaying wood. In fact, the larvae are easier to find, and findable over a longer season than the adults, and can usually be quite easily identified to species in the field.

Schizotus pectinicornis larva with a pair of curved cerci.

Pyrochroa coccinea larva. Both Pyrochroa species have a pair of straight cerci. P. coccinea lacks a complete, raised, transverse line across the 8th tergite near the base, present in serraticornis larvae. But 1st instar larvae of these two are more difficult to identify to species.

A well-illustrated key to larvae was provided by van Emden (1943).

References

Buck, F.D. (1954). Coleoptera (Lagriidae, Alleculidae, Tetratomidae, Melandryidae, Salpingidae, Pythidae, Mycteridae, Oedemeridae, Mordellidae, Scraptiidae, Pyrochroidae, Rhipiphoridae, Anthicidae, Aderidae and Meloidae). Handbooks for the identification of British insects, vol. V, part 9. London: Royal Entomological Society. Out of print but available as a free download here.

van Emden, F.I. (1943). Larvae of British beetles. IV. Various small families. Entomologist’s monthly magazine, ?78?(1943), 209 – 223 and 259 – 270.


10 Comments

  1. Judith Evans says:

    Found a Black-headed Cardinal beetle hiking around the rim of my garden rubbish container. I grabbed my camera and snapped away as I’d never seen a bug like him. His wing case was open to reveal a shiny black body underneath…..really beautiful.
    I live in rural West Sussex surrounded by trees of all types; he certainly seemed to enjoy sitting on a bright green rhododendron leaf, before he disappeared into the depths of the garden rubbish.

  2. markgtelfer says:

    Good stuff Judith, I once saw a Cardinal beetle fly across my garden but couldn’t tell which one it was.

  3. Susie Spragg says:

    Seen an unusual big red beetle in garden. Wing case more of a shiled shape that the Cardinal. What could it have been? Definitely much bigger than a lily beetle , of which I get a lot. It was on a currant bush in Surrey/W Sx borders

  4. markgtelfer says:

    Susie, I’m not sure. Maybe Chrysomela populi, though if so it would have wandered onto your currant bush from nearby willows or poplars.

  5. John Graham Guest says:

    There were 7 cardinal beetles, Pyrochroa serraticornis on my Fritilaria lutea plant as it had finished flowering, 2 mating pairs and 3 individuals, something was making holes in the leaves.However they were the only animals present.

  6. markgtelfer says:

    John, Red beetles making holes in lily leaves will be the Lily Beetle Lilioceris lilii. Google on the scientific name and you should find plenty of info. It’s a leaf-beetle (family Chrysomelidae) rather than a cardinal beetle.

  7. Martin Corby says:

    Just seen what I think is a red-headed cardinal beetle on my window sill…..but isn’t it a bit early? Definitely had a red head.

  8. markgtelfer says:

    Martin, sorry for late response. Red-headed Cardinal is a fairly unmistakeable beetle. Perhaps yours emerged from firewood indoors, thinking it was spring already?

  9. Claire says:

    I have a delivery of firewood infested with red headed cardinal red beetles. I live in 500 yr old timber framed cottage and the wood is stored in a timber framed log store, part of the house. Will these already infested logs lead to the timber of my house being destroyed? I have never seen so many beetles, if you bring in 6 logs.at least 40 to 50 beetles appear within half an hour!!!

  10. Roger says:

    Posting from the Dordogne, France. Like Claire, I have seasoned oak firewood that’s full of Black-headed Cardinals. I know they’re in the wood because I come across a few while splitting it. As soon as the wood warms up next to the stove they zoom around the room, normally while we’re watching TV. I don’t think they’re harmful because they soon die even indoors and especially when they’re put outside in the cold.

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