“I will be lurking around the Cassiobury Park entrance at ten thirty. I will be able to stay until midnight which should be plenty of time.
I had never met Dave Murray of the Watford Coleoptera Group before. He has been working Cassiobury Park and Whippendell Woods for beetles for several years and, as I found out on Friday night, knows the place and its beetles like the back of his hand. After meeting up at the appointed lurking place, Dave took me straight to a lime snag in the Park, I flicked my headtorch on and there was Uloma culinaris!
Uloma is a smart, polished mahogany beetle that the WCG discovered and is still only known from Watford, and from an old record by G.B. Alexander: “Bushy Hall, in rotton wood, 20.vii.1950”. We saw at least six individuals, all on this one trunk, along with a few other saproxylic beetles: loads of Endomychus coccineus (Endomychidae), 1 Triplax aenea, 1 Dacne bipustulata (both Erotylidae) and a few Lesser Stags Dorcus parallelepipedus (Lucanidae). Uloma culinaris is not regarded as a native species, at least not by Alexander et al. (2014). I can’t really disagree, except that it would be nice to think that Uloma has been lurking in the darkness on Watford’s ancient trees since way back, until Dave and co. shone a light on it.
Achopera alternata is another startling discovery by the WCG. It’s an Australian weevil, certainly not native to Britain that was first found at Erddig in Wales by John Bratton (see Beetle News of May 2012). Rowan Alder made an online discovery of a second Welsh locality (apparently photographed somewhere near Llangollen). But the place to see this weevil is Cassiobury Park where Dave and co. have seen it in numbers on some of the stumps. We saw three on exposed sapwood of a beech snag. Even though this is not a small beetle (6 mm), they are quite difficult to spot: cryptically patterned, dull and sloth-like. Through the hand-lens, I watched this one nibbling away at the surface, presumably grazing algae?
If you weren’t specifically searching for Achopera, it would be really hard to see, and I wouldn’t mind betting that this beetle is more widespread than we currently know.
Amongst some of the other saproxylic beetles seen on the night were 4 Colydium elongatum (Colydiidae) and a couple of dozen Teredus cylindricus (Bothrideridae), both species that are much easier to see by torchlight.
Many thanks to Dave for the guided tour, and for the humbling insight into what can be achieved by thoroughly working your patch (rather than gallivanting all over the country getting a big pan-species list!).
Alexander, K.N.A. Dodd, S. and Denton, J. (2014). A review of the scarce and threatened beetles of Great Britain. The darkling beetles and their allies. Aderidae, Anthicidae, Colydiidae, Melandryidae, Meloidae, Mordellidae, Mycetophagidae, Mycteridae, Oedemeridae, Pyrochroidae, Pythidae, Ripiphoridae, Salpingidae, Scraptiidae, Tenebrionidae & Tetratomidae (Tenebrionoidea less Ciidae). Species Status No. 18. Natural England.