Our star species in this month is a summer visitor to the UK, the Hornet Mimic Hoverfly (Volucella zonaria) of the family Syrphidae, also known as Belted Hoverfly. Although it looks very similar to the European Hornet (Vespa crabro), with black and yellow stripes across its abdomen, it is absolutely harmless to humans. The fly mimics the Hornet both in size and in the appearance, and even makes a similar buzzing noise while flying.
Adults of the Hornet Mimic Hoverfly can reach 2 cm in length, and as such it is the largest hoverfly species in the UK. Its yellow face and forehead, big eyes and orange-yellow and black stripes on the abdomen are its characteristic features. V. zonaria is a migratory species, occurring from the Mediterranean across most of Europe and further to the east. In Great Britain, it can be found from May to October, visiting flowers in parks and gardens, before flying back to the mainland in the autumn. Females lay hundreds of eggs in wasps’ nests, where the larvae are scavengers, eating debris at the bottom of the nest cavity.
Hoverflies feed on nectar and pollen; they can carry and transfer pollen while foraging, even over long distances, especially during migration. Migratory hoverflies are considered to be the second most important pollinators, after bees. Hoverflies do not appear to be as hairy as bees but most of the species have small hairs covering nearly the entire body. The pollen grains stick to hairs (in less quantity than on bees) but the pollen can be transported and transferred from flower to flower more often and very effectively. Further research is needed in terms of understanding foraging movements, especially for migrating species.
Approximately, four billion hoverflies travel to and from Britain every year. They play an essential role as key pollinators and sometimes their ecological services are largely underestimated. Some of these ecological services include pest control, nutrient recycling and crop protection. For example, trillions of aphids are eaten by hoverfly larvae, and they also represent valuable food resources for birds, bats and other predators. Populations do not seem to be decreasing dramatically, however, there is a necessity to study their response to environmental changes, especially caused by human activities (e.g. effects of pesticides and agrochemicals), and how they could be beneficial in sustainable agriculture (Pollination by hoverflies in the Anthropocene).
Hornet Mimic Hoverfly has expanded its geographic range and appears to be more common in England now, especially further north. This extension in distribution could be resulted from a climate change. Before 1940, the species was recorded as very rare and only known from two specimens collected in the south. In Manchester Museum’s entomology collection, there are 20 specimens, mainly collected from Bournemouth, Essex, Surrey and Middlesex between 1958 and 1987.
Records across England from iNaturalist, a citizen science nature recording app, show 734 verified observations of Volucella zonaria since 2015, mostly concentrated in the south and midlands, with one record further north in Kendal, Cumbria (see on the map).
Of the threats the Hornet Mimic Hoverfly encounters from humans is the confusion in its appearance with the European Hornet (Vespa crabro) and with the Asian Hornet (Vespa velutina), especially when it comes indoors, resulting in many innocent deaths. The Wildlife Trust has created an identification guide with images and information to help separate the hornets and the lookalike hornets. Next time you see a ‘hornet like’ flying creature look twice before you harm or disturb it; it could be the Hornet Mimic Hoverfly!
Resources:
Entomology Manchester 