What's the model for this mimic?

Hoverflies, without stings, are well known for mimicking the colours and patterns of stinging wasps so the standard issue markings for most hoverflies are some variation on the theme of black and yellow stripes. This species, Leucozona glauca, is the exception to the rule and is turned out in this attractive black and denim blue colour scheme ...... which begs the question as to whether it's mimicking something or is simply a genetic variant with no particular natural selective benefit or disadvantage. 

According to British Hoverflies by Alan Stubbs and Steven Falk the markings on this species are normally yellow but this blue variant occurs frequently.  I haven't encountered it often and this one is part of a population that lives along a woodland ride in Hamsterley Forest, Co. Durham and is often quite abundant when hogweed and angelica are in flower. This individual is a female, identifiable by the widely spaced eyes.

It seems to have been quite a good summer for some hoverflies in my part of Co. Durham. I had a quite a few of this one, which I think is a particularly attractive variant of Helophilus pendulus, in my garden where it seemed to be partial to meadow crane'sbill flowers. 

I'm not completely sure what this large hoverfly species is but I think it may well be Sericomyia  silentis..... a convincing wasp mimic. It's been quite common in Teesdale throughout August and early September and I've seem several on  devil's bit scabious, which is supposed to be particular attractive to this species.

Watching the (Insect) World Pass By...

Sometimes the best way to watch wildlife is to just sit still and let it come to you, and in our garden at the moment the best place to sit is next to this plant - dame's violet a.k.a. sweet rocket a.k.a Hesperis matrionalis. In addition to having a powerful carnation fragrance and being the food plant of the orange tip butterly caterpillar it's a real butterfly magnet and while I watched it was constantly visited by ....

... small whites and ....

... red admirals. Sweet rocket produces such an abundance of nectar-rich flowers that the butterflies are reluctant to leave and just clamber from flower to flower ..

... which gives you plenty of time to admire the intricate patterning on the underside of their wings.

After you've been sitting in one spot for a while you begin to notice things that you might never spot if you were on the move, like this unidentfied green caterpillar resting in the shade of a chive flower stalk.

Then other visitors begin to turn up - this is Tachina fera, whose larva is an internal parasite of noctuid moth caterpillars and which I've never seen in our garden before. It seems to have a real liking for forget-me-nots.

The sweet rocket is the current butterfly attraction in the garden but the focus of bee visits (particularly leaf-cutter bees) is the wood vetch Vicia sylvatica which attracts a constant stream of visitors. This is a very attractive plant that climbs through the surrounding vegetation and produces a large number of racemes of flowers over a long period.

If you sit in the sun for long enough - especially near the garden pond - then this hoverfly Helophilus pendulus almost always turns up. You can find some wonderful photographs of this species laying eggs - and pictures of its eggs and larvae - here