Last week I witnessed a strange phenomenon at the kitchen garden pond. The entire water surface was covered in a dusting of white flecks. It seemed to me that these were hatching flies of some kind, but it was not obvious what they were to the naked eye (not to my declining ones anyway). I returned with a macro lens to discover a flotsamic mess of drowning insects and shed skins. Where any plant protruded from the water it was covered in survivors as were the lilly pads and their flowers. This was, I was to discover, an explosion of Water Lilly Aphids.
As I tried to photograph these 1-3mm long sap suckers I began to notice all the predators in attendance. Lots of pond skaters and backswimmers, but more to my amazement was witnessing a tiny parasitic wasp come and inject her egg(s) into a hapless aphid (who was perhaps at the time wondering how it had had the good fortune to avoid the drowning fate of so many of its siblings).
On reviewing my photos I then saw more than one aphid carrying what looked like fly eggs on their backs. These I now believe to be hover fly eggs. I can't imagine the aphids have a particularly long life, so both wasp and fly larvae must develop very quickly, perhaps moving onto a secondary host if they themselves outlive the aphid?
Anyway, the moral of the ongoing story is that just because there are no fish in a pond it doesn't mean nothing is going on.
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