Greater Hornet Plumehorn (Volucella zonaria) Size: 15.5-19.5mm Flight:
May-Nov
Species of the week – 6th October
This our largest hoverfly (In the U.K) and if you have seen one
you can probably understand why it’s often mistaken for the European hornet Vespa crabo, and with
good reason. Its markings mimic the hornet in both colouration and design, a
classic example of Batesian mimicry. However, this hornet mimic will not sting,
bite or get aggressive defending a nest, as doesn’t have one and is often seen
late summer and into autumn on a warm day.
Hopefully this illustrates better than I regarding similarities between the two
species and why zonaria is a great mimic.
This hoverfly arrived in the 1930s and soon became established in
the London area in the 1940s. Since then and with the help of climate change it
has been moving steadily north. I first came across it in the Yorkshire region
in 2021, before this I recorded it in the Olympic Park in London 2016. It was
1st recorded on the NatureSpot website, which covers the Leicestershire area,
in 2008 and listed for the Attenborough Nature reserve (Nottingham) in 2007.
According to NBN it arrived in Yorkshire in 2015 and has reached the borders of
Scotland within the last few years.
It’s a good day when you spot this hoverfly and its often found in
urban parks and gardens visiting the butterfly bush Buddleia. It is
distinguishable from its yellow and black-banded abdomen, tergite 2 (closet to
the thorax) being chestnut in colour along with the scutellum. Its smaller
cousin the Lesser Hornet Plumehorn (Volucella inanis) is more yellow on tergite
2. Both have orange-yellow wings and typically there is a dark spot near the
wing tip. Both have a yellow face but the other feature that distinguishes it
from other hoverfly tribes are its feathery plume antennae. The plumehorn
antennae is not too dissimilar to the antennae of some macro moths. No doubt
these antennae like the moths, are used for detecting chemical cues, an evolutionary
adaptation to help it find mates, floral scents of flowers to on feed on pollen
and nectar, possibly even for locating nests of social wasps and hornets.
The hoverfly’s mimicry of a hornet allows access to hornet and
wasp nests where the female will lay its eggs. The larva is carnivorous,
feeding on the detritus and dead larvae within those nests, thus acting as an ectoparasite.
For those interested there was a video posted on the YouTube site Ramblings of
an Entomologist by Trevor Pendleton, super naturalist, of a hornets nest he has
been following throughout the year. Amazing video, but two things to mention, the
detritus at the bottom of the nest highlights how a female hoverfly could get
close enough to lay an egg from which any larva could hatch, feed, and survive.
The second being in this video you can see how the hornet guards the
nest, to prevent anything from getting inside, so I do wonder how close a hornet
mimic could get, even with its disguise.
Anyways here is the video link do check it out.
From a tiny acorn, a mighty Hornet nest can grow:
https://www.youtube.com/watch?v=oo6aMjrtTUI
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