Wednesday, 6 March 2013

With the sun came flies

Yesterday, 6th March, was the warmest and sunniest day of the year so far. The ivy, normally quite a sombre plant, was transformed as its polished leaves gleamed in the sunlight. Flies basked, both on these leaves and on tree trunks, fences and gateposts. They cannot afford to relax too much; a Zebra Spider, Salticus scenicus, had been roused from its torpid winter state and was in the prowl! This spider was, surprisingly, a new record for the Pocket Park.
Winter-flowering Heather. 6 March, 2013

I looked in at the burial ground adjacent to the Pocket Park. Clumps of snowdrops were attracting Honey Bees, Apis mellifera, and with them were several Drone Flies, Eristalis tenax. These flies are in fact a species of hoverfly and, despite having only two wings (whereas bees have four), are quite good mimics of honey bees - presumably convincing enough to deter birds. They seem confident in the immunity conferred by their appearance and can often be plucked by the wing from a flower and released unharmed. Bees tend to approach a flower on a cautious zig-zagging flight path whereas a hoverfly will use a more direct approach but then pause motionless for a few seconds before alighting. Both have reasons for their heedfulness as inside the flower may lurk a predator such as Misumena vatia, a spider able to change colour to pink or yellow and so match the background. Beside some of the headstones were clumps of Erica carnea. This winter-flowering heather was also attracting lots of bees and a poet could doubtless pen a thoughtful line about this proximity of life and death. A Brimstone butterfly, Gonepteryx rhamni, flitted by.

The flies inevitably turned out to be commonplace species but these early records are nevertheless of phenological interest, all being earlier than my insect handbooks indicate.

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