Monday, September 21, 2009

Fatal Attraction

As the nights draw in and the lights go on earlier each evening, increasing numbers of insects are drawn to the light at windows. The local spider population seems to be aware of this, judging by the network of webs spun across our windows each morning, often capturing this little fly, known as an owl midge.

Owl midges, sometimes called moth flies, are only about 3-4mm. long so don’t make much of a meal for a spider. Their single pair of broad ‘delta’ wings, reminiscent of those of a moth and fringed with hairs, are a distinctive feature, but they seem to spend as much time running around on vegetation as in flying.

These flies, whose larvae feed on decaying vegetation in damp places, have a distinctive hump-backed profile and are covered in rosettes of hairs, especially on the thorax which, when viewed from above, is supposed to have a fanciful resemblance to an owl’s face, between partially outstretched wings.

You can find these little flies all-year-round but in spring they seem to be attracted to wild arum Arum maculatum flowers (below)

Open up the chamber at the base of the Arum inflorescence where the flies are imprisoned by this plant and you’ll often find owl midges inside.

Scarlet wild arum fruits (below), which are a conspicuous feature of hedgerows and woodland edges at this time of year, are often the work of this minute pollinator.

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