Sunday, 15 May 2016

Borough Hill in May

The weather forecast had not been promising but a visit to Borough Hill by the Northants Dipterists' Group proved to be very successful. Warm, sunbathed leaves were occupied by insects such as ladybirds and beetles whilst spiders were represented particularly by specimens of the Nursery Web Spider, Pisaura mirabilis.

Pisaura mirabilis, a very common spider on Borough Hill.
15 May, 2016

These rather large creatures needed to be approached with care; should a shadow fall across them they scuttled away at lightning speed. This species is the only representative of its genus in Britain and is quite unmistakeable.

St Mark's Day is 25 April but, though a little late, St Mark's Flies, Bibio marci, were present in large numbers. The larvae are under some suspicion of damaging agricultural crops but there is evidence that the adults may assist in pollinating flowers. So that's ok then!

St Mark's Fly. They were running about three weeks late!
Borough Hill, Daventry, Northants. 15 May, 2016

With their slow, bumbling flight they are probably - for a short period at least - an important food item for swallows and other insectivorous birds. The photograph shows a male - note that the large compound eyes more or less meet in the middle. These eyes are very hairy, giving them a slightly fuzzy appearance.

As mentioned in an earlier blog, the soil on Borough Hill tends to be neutral or slightly acid.  There were snails there but in relatively few numbers as they require lime to build their shells. By investigating soil tussocks I was able confirm that slugs - not dependant on lime - were relatively common. Woodlice also have 'shells' impregnated with lime and were not numerous, but I was pleased to find a Pill Millipede, Glomeris marginata.

Glomeris marginata, a millipede often mistaken for a
woodlouse. Borough Hill, Daventry. 15 May, 2016

This creature can easily be mistaken for one of the 'roly-poly' woodlice (Armadillidium species) but the structure is really quite distinct. They are glossy and dark brown to black, unlike the matt greyish tones of most woodlice. 

Familiar shieldbugs were present too. Woundwort Bugs, Eysarcoris venustissima, were plentiful and in virtually all cases had paired up. I detected no Woundwort but White Dead-nettle, an alternative food source, was plentiful.

Woundwort Bugs in copula. Borough Hill, Daventry,
Northants. 15 May, 2016

Common, but not quite as abundant, were examples of the Dock Bug, Coreus marginatus. Although invariably included in books about shieldbugs it is not a true member of the group as it only has four segments to each antenna. It is highly distinctive and, being common, most wildlife enthusiasts are familiar with it, particularly as its food plant, various dock species, is abundant nearly everywhere.

Dock Bug - but not on dock. Borough Hill, Daventry,
Northants. 15 May, 2016

So an unexpectedly useful day and I arrived home with  enough specimens to keep me out of mischief for days.

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