Friday, June 30, 2006

Brown argus, Aricia agestis, in Hastings

I recently saw a brown argus butterfly in another visit to the Marline Valley meadows, an SSSI on the western outskirts of Hastings. These butterflies are markedly smaller than the common blues that they fly alongside and the males as well as the females are brown.

Although quite common in places on the chalk, this butterfly seems to be rarely seen elsewhere in Sussex and, where it does occur, it is usually on, or near, the coast. The main foodplant of the caterpillars is rock-rose, Helianthemum chamaecistus, but this does not occur in Sussex away from the chalk, so the Marline larvae are probably eating the alternatives of stork's-bill or dove's-foot cranesbill.

The butterfly was recorded from Marline Meadows in 1989 and it is good to know that a colony is still there. As Jeremy Thomas says in his Butterflies of Britain & Ireland populations away from chalk, limestone or dunes are "invariably small and very rare."

The first generation adults are probably over by now, but there should be a larger second generation from late July to early September.

Saturday, June 24, 2006

Lesser stag beetle, Dorcus parallelipipedus

The female lesser stag beetle shown above appeared in our bedroom the other night (the smaller mandibles and two bumps on the forehead distinguish it from the male). I think it probably exited from a log of dead birch wood I had brought home earlier in the day as this species spends its early stages in such habitats.

The lesser stag beetle turns up from time to time in our part of East Sussex but there are no authenticated records of Lucanus cervus, the stag beetle proper. This is a bit of a mystery as this is a heavily wooded area with plenty of suitable habitat and the species seems common enough in surrounding areas. I often thinks that gaps of this kind occur because, at some time in the past, the species has been locally wiped out by a predator, parasite or disease. Sometimes, of course, they come back again, like the hornet that appeared widely in East Sussex (or reappeared) about four of five years ago and now seems perfectly happy.

Male lesser stag beetles have bigger 'antlers' that the females, but nowhere near the size of the males of their larger relative. Anyway, our lesser stag beetle, after posing for her photograph, was released into the garden.

Sunday, June 18, 2006

Ctenophora nigricornis - an unusual cranefly

One of the more spectacular insects I have seen this year in Brede High Woods is this cranefly that fancies itself as an ichneumon.

Ctenophora nigricornis is a Red Data Book species that breeds in dead timber in ancient woodland and, although widespread in Britain, there have been very few recent records. In East Sussex the only other sighting is from St. Dunstan's Farm near Rushlake Green. The horn-shaped ovipositor is for penetrating dead wood.

A curious thing about these and some other flies is why they look somewhat like ichneumon wasps. So far as I know, icheumon wasps are not especially distasteful and the only thing they sting is their host when they lay an egg, so is it a defence strategy, or just an effective camouflage? The irregular red and black patterns may look like dappled sunshine and shade, though the insect in this picture was very obvious as it stood four square on a leaf.

Wednesday, June 14, 2006

White-letter hairstreak larva and pupa

Another treat from Brighton recently was finding a caterpillar of a white-letter hairstreak, Satyrium w-album. It was on a plant of white dead-nettle, although its foodplant is elm. Presumably it had been blown out of its tree (Brighton is well-known for its elms).

After a day or two in pupated and the characteristic pattern of this particular butterfly species soon developed.

The white-letter hairstreak population nosedived following the devastation of Dutch elm disease, but has since recovered quite well and is now widespread in South East England. It is, however, a rather difficult butterfly to see as it usually skulks about in the treetops.

Biodiversity in Brighton

Recently, at the invitation of the Sussex Biodiversity Record Centre, I joined in a field trip to Preston Park in Brighton. Sussex recorders of the various groups have been having two of these trips each year, partly with the aim of filling some of the data gaps, and partly just to meet one another and learn more about the work that is done on the different groups. This was our first 'urban' outing.

The picture above shows some of the group scrutinising the flora and fauna around a small pond in the park's wildlife area.

We also covered two local wildlife-friendly gardens to see how these compared with the park. One of the plants we saw here was green alkanet, Pentaglottis sempervirens (see other picture) An enjoyable day and our thanks are due to Matthew Thomas, the city ecologist, who worked with the Record Centre's Penny Green on the detailed arrangements.

Sunday, June 04, 2006

Twenty-plume moth (Alucita hexadactyla)

A little visitor to our windowpane last night was a twenty-plume moth, Alucita hexadactyla. This species is the only British member of the family Alucitidae. The adults are very long-lived, emerging in August before going into hibernation and reappearing in May and June.

The larvae live in the flowers of honeysuckle where they feed mainly on pollen and move from flower to flower.

Thursday, June 01, 2006

Mother Shipton & Burnet Companion

On a recent walk under the transmission lines in our local woods, I came across two day-flying moths that are sometimes confused with the grizzled and dingy skipper butterflies.

One (top picture) was the brown and yellowish burnet companion, Euclydia glyphica, and the other a Mother Shipton, Callistege mi.

Mother Shipton was a wise woman who lived in Yorkshire in the 15th and 16th centuries. She was reputed to have "a nose of an incredible and unproportionate length" as in the pattern on the moth's forewings. The scientific name 'mi' is Latin for the Greek letter 'mu', supposedly evident on the hindwing, though I think one has to have a fairly strong imagination to pick it out.