There used to be a small pond down at the bottom of our garden that began to leak badly (couch grass rhizomes speared through the butyl liner) so I left the leaky liner in situ, filled in the pond and planted it up as a bog garden with plants like yellow flag, purple loosestrife, meadowsweet and figwort. The last three species are in full flower now and attracting swarms of this attractive little hoverfly, Episyrphus balteatus
This is one of the easier species to photograph in flight, staying more-or-less stationary for long enough to focus. It's interesting to see that the wings are rotated at various angles during the hover - it's not just an up-and-down wing movement, more a figure of eight. Interesting too that this complex wing movement is all controlled by the musculature in the thorax, since there are no muscles in the wings.
Delightful little insects - the harrier jump-jets of the insect world..... but maybe there's a slightly darker side to their activities....
These are useful insects, whose larvae feed on aphids, and normally the adults feed on pollen - and so pollinate flowers - but a lot of them have found their way into my greenhouse and are feeding obsessively on the powdery mildew on the cucucumber leaves (it seems to be a particularly bad year for this disease)
You can see the tongue of the insect picking up mildew spores here - but you can also see spores clinging to other parts of its anatomy - e.g. on hairs just to the left of the leg.
Episyrphus balteatus often forms dense migratory swarms, so I imagine that when they travel around they can carry fungal spores with them, and so also transmit fungal diseases. It would be interesting to see what fungi can be cultured from the spores carried on their bodies.
On balance, though, attractive, useful, fascinating insects.