Insect in the spotlight: Hornet mimic hoverfly

 

…or the BFG (Big Friendly Giant) amongst the hoverflies!

Over the course of a couple of weeks now, I’ve been seeing this insect on and off. But as you can probably imagine, it is quite hard to take pictures of flying insects. Fortunately though, my assistant photographer (a.k.a. my dad) was able to capture this insect on camera and asked me afterwards which insect it was.

You can enlarge the images by clicking on them.

When I first encountered the hornet mimic hoverfly (Volucella zonaria), I thought that it might be able to sting, because of its size (it is the largest hoverfly species in the Netherlands!) and colouration. But upon closer inspection, it appeared to be a harmless hoverfly, which likes to pretend that it is more dangerous than it actually is. Such a phenomenon is called mimicry and this one pretends to be a hornet (as the name suggests).

http://eenbijhoorterbij.nl/Wesp_pagina_RESERVE/Wesp%20Hoornaar.htm
European Hornet (Vespa crabro)
Hornet mimic hoverfly
Hornet mimic hoverfly (Volucella zonaria)

 

In reality this insect cannot sting or bite, but makes itself useful as a pollinator. The main differences between a hornet and the hornet mimic hoverfly are body size (the hornet is slightly larger and has a pronounced waist), length of antennae (hornet has larger antennae), shape of eyes (the eyes of the hornet mimic hoverfly are more round, whereas those of the hornet are elongated) and the hornet has 4 wings instead of 2. You might say that it is very easy to distinguish between the hoverfly and the actual hornet, but some research suggests that birds and perhaps other animals are fooled, because some aspects of the hoverfly resemble those of the hornet. Those animals will generally avoid the hoverfly and leave it alone while it sips some nectar. Better to be safe than sorry!

An interesting fact about the hornet mimic hoverfly is that it spends its ‘childhood’ as a larvae in wasp nests. Even then it is friendly towards its host, because it eats dead wasps and other waste the wasps produce. Scientists are not entirely sure why and how the hoverfly infiltrates the nest. Especially the how question is of interest, since wasps tend to defend their territory against intruders. Perhaps the hornet mimic hoverfly secretes the same smell as the wasps and by smelling like a wasp, it gets past security checkpoints unnoticed. A spritz of Eau-de-Wasps anyone?

 

Extra information about research on hoverfly mimicry:

http://rspb.royalsocietypublishing.org/content/269/1489/411.short

http://beheco.oxfordjournals.org/content/18/2/337.short

http://www.repository.naturalis.nl/document/124832

http://rspb.royalsocietypublishing.org/content/274/1621/1949.short

http://www.jstor.org/discover/10.2307/49851?uid=3738736&uid=2&uid=4&sid=21104365619927

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