Batman hoverfly

From the willows by Village Green’s pond, Ian has sent us this image of another new species for the reserve’s lists: Myathropa florea, the Batman hoverfly.

The Batman hoverfly is a large colourful nectar and pollen feeder. Its black and yellow colouration, including the Batman logo on its thorax, is a disguise. In the invertebrate world black and yellow stripes mean danger and the defenceless Batman hoverfly is wearing them to scare away predators.

However scary a harmless adult Myathropa florea may look, it is nothing compared to its larva, which is the thing of nightmares. It is a rat tailed maggot, up to an inch long, with an extendable breathing tube two or three times its body length at its posterior end. It lives in stagnant water pooled in rotting wood and waterlogged soil, and the tube enables it to breathe air (yes, they breathe through their bums…) from the surface while it forages for bacterial food among the detritus on the bottom of the pool. It has a taste for animal faeces and the noxious puddles that form around dung heaps.

The larvae undergo three moults, overwinter as pupae* and usually hatch into adults the following summer, although there are times when the pupal stage can be extended for up to two years. The adults live for only three or four weeks, feeding among wildflowers and in gardens.

The species is widespread across the UK, and common.

*There is disagreement about this: some authorities say this species overwinters as a larva and that it is the larval stage that can last as long as two years. Information about the life cycle of Myathropa florea is sparse.