UNWANTED ADMIRER Horseflies find humans irresistible.
Country Sights and Sounds
I first met Clarissa in the shade of that big willow that grows with its root in our small stream, and she followed me along the narrow path that wends its crooked way to the tall reeds where the wagtail family gather to roost. I waved her away more than once, but she is nothing if not persistent. Rather than take a hint she stayed a pace and a half behind – just out of striking distance, as if she knew my temperament, and how the oppressive humidity had shortened my mood to the point I was liable to lash out.
When I stopped to admire the golden blooms of greater bladderwort, an unusual insectivorous plant occasionally found in areas of shallow, standing water, I felt a light touch on my arm and there she was, her green eyes glowing in the sun and her mouth set firm with determination.
I could have allowed her her will, but instead swung my open hand, at which she drew back, though only for a moment. Again there was the lightest touch, which this time brought a quicker and more effective response. Catching her with a glancing blow, I sent her spinning to the ground, where she lay on her back amid struggling grasses and early, purple-tinged flowers of lesser butterwort and was soon under my foot.
Satisfied she would bother me no more, I picked her up and looked more closely into those eyes. Were there any more lovely? Though staring wide and unblinking they shimmered green and hot orange, in stark contrast to her brown body, so brown it might have come straight from the bog.
What could I do with her now? The butterwort gave me an idea. I fed her to that hungry, insect-eating plant by placing her almost lifeless form on one of those yellow-green, triangular shaped leaves, and watched as her last struggles caused the leaf edges to curl up and hold her fast.
I hate horseflies. Clarissa was just one of many I met that day. They are early this year – that sudden burst of summer brought everything forward, so that we missed the best part of a month, springing, as it were, from a protracted April into sudden June, with a generation of wild flowers passing in a very short time.
The common butterwort has a longer season than most. While its roseate of pale leaves can be found throughout most of the year, the pale purple flowers appear singly on thin stems from May right through to the cool nights of late September. It likes to grow on wet ground from which most other more vigorous plants are excluded.
Although it has a rudimentary root system that acts better as an anchor to keep the plant tethered to one spot than as a feeding mechanism, small insects provide most of the nutrients it needs to get by, with midges making up the main part of the diet. Such a fine prize as Clarissa would be a rare feast indeed.
When an insect lands on the upper surface of a butterwort leaf it finds its feet trapped by a sticky fluid. In response to the struggles of the hapless captive, the outer edges of the leaf curl upward to prevent escape, while special glands are stimulated to release a digestive enzyme that dissolves the nitrogenous elements contained in the prisoner’s body. Our world is full of wonders.
Clarissa and her kind are nothing short of a plague. It isn’t perhaps that there are so very many horseflies, but that they simply do not give up, and the death of a mere one is often the signal for two more to appear on the scene. Kill two and four arrive. If they sucked the blood only of horses and cattle we should be satisfied. But no! Human blood is equally if not more in demand.
And how is it they have mastered the art of switching that alarming buzz (with which they announce their arrival and their intentions) on and off at will? So they sound behind and when we turn to look they switch off and dive in silently from another direction.
For such large flies they are able to move with surprising delicacy, and can land on a moving limb so softly that we might not notice at all. Then the jaws are swiftly applied. As the initial incision is made, so a clever mix of anaesthetic and anticoagulant is applied in order for the meal to proceed according to plan. All horsefly bites come from female insects, which need a feed of blood if they are to produce viable eggs. The males are much more gentile, feeding only on nectar.