The Way I See Things


Empis tessellata

This is the largest UK species in the Empididae family, which are commonly called dagger flies, balloon flies or sometimes dance flies. The first of these names is the one that makes most sense to me, because they mostly have a long proboscis, which is equally well adapted to feeding on nectar and to piercing the bodies of other invertebrates.

Empis tessellata frequents woodland and hedgerows, has a particular liking for hogweed, and is frequently found in gardens. At the moment I seem to be seeing them everywhere, and I've photographed several specimens over the past few days. I found this one at Grove Hill this morning, and the rather striking pose it adopted on the bramble gave me some (slight) compensation for the fact that there were Nodonata (©) present at a reserve that should have been teeming by now with damsels and dragons. That's a worrying situation, clearly, and I'll be wanting to make a return trip, maybe next week, to see if the situation has improved.

Returning to E. tessellata, you may be able to see that the eyes of this individual are contiguous, which shows that he's a male, the eyes of females being quite widely separated. This species is both nectar-feeding and predatory; Wikipedia states that only the males kill other insects, but I haven't found another authority for this claim. What is widely agreed is that if the male wants to secure a mate, he needs to catch and kill another invertebrate, and present it to his inamorata as a nuptial gift. Only if she accepts the offering will she allow him to mate with her, while she gets on with eating the gift. Following a successful mating, larvae of the next generation will develop through the winter months in leaf litter, where they predate the larvae of other flies.

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