Introduction

INTRODUCTION What are hoverflies? Hoverflies come in many forms, and their A number of hoverflies are excellent appearances can vary greatly. They are par- mimics of wasps, for example, Temno sto - ticularly well known for imitating wasps, ma, Ceriana and Spilomyia. They resemble bees or bumblebees. Wearing striking yel- wasps in many ways. Ceriana has devel- low and black markings, a brownish hon- oped long antennae on a protuberance on eybee-like pattern with pale body mark- its head to mimic the long antennae of ings, or having a furry bumblebee-like wasps. Temnostoma has short antennae, but appearance all help to deceive predators. waves its blackened forelegs in front of its Hoverflies don’t just look like their mod- head. The bodies of Spilomyia and els, they often behave like them. You some- Temnostoma are broad and rounded, just times find that the wasp which has been like those of social wasps. In flight, they buzzing around some vegetation turns into a hoverfly when it lands on a leaf! This is called mimicry. Predators learn to leave stinging insects alone and will hesitate before catching anything that looks like them, giving the hoverflies time to escape. Not all hoverflies resemble stinging wasps, bees and bumblebees. A group of hoverflies (including Xylota) look like sawflies, which are biting wasps. Although sawflies do not sting, they are also disliked by predators, for example Brachyopa. Other hoverfly species are dull brown and black and seem to rely on cryptic colours to hide from predators. They are often found in or around vegetation. Some of these species appear quite similar to common flies of the Muscidae family and are easily overlooked. photo 1. The wasp mimic Chrysotoxum The following paragraphs introduce the bicincta (N. Schonewille) different hoverfly body forms and show how the flies look. This will help with ‘on the spot’ detection of species, by demon- strating what might be a hoverfly (and what might not). Wasp mimics. These hoverflies copy the yellow and black body colouration of wasps (Photo 1, 2). Most also bear some resemblance to wasps in terms of colour pattern, form or behaviour. For example, Eupeodes and Syrphus have yellow and black stripes, but their body form and behaviour are quite different from that of wasps. They have short antennae, a broad flattened body and hover. Their appearance may still be convincing for laymen; once I photo 2. A real wasp; note the folded wings, was forbidden to pick up a ‘wasp’ that was kidney-shaped eyes, and long antennae clearly a Syrphus! (N. Schonewille). 7 display the same erratic flight pattern as black with yellow bands and a white wasps, which is quite convincing because abdominal tip). The latter group is the their quick movements help to hide their model for the plumata variety of the hov- true body forms. For the skilled observer, erfly Volucella bombylans (photo 5). Other these hoverflies betray themselves when colour patterns also occur; Arctophila fulva they settle. They sit still in one place with and Criorhina berberina oxycanthae are their wings unfolded, when real wasps entirely yellow-haired, and resemble pale- would begin to walk around and social haired bumblebees such as Megabombus wasps would also fold their wings. For me muscorum and pale forms of Megabombus the best wasp mimic is Sphecomyia, a rare pascuorum. Hoverflies differ from their boreal species, which remains a convinc- models as they have short antennae (none ing wasp mimic even when dead and of the Northwest European bumblebee pinned as part of a collection. mimics have developed long antennae), There are also some small, elongate hov- relatively large heads, and display typical erflies that exhibit yellow or grey spots or quiet hoverfly behaviour. One of the best bands on a black abdomen. I find difficult bumblebee mimics is Pocota personata to believe that they are mimicking wasps, (which resembles B. terrestris and B. luco- even the small solitary wasps (Photo 3). rum), since it even has a small head. These hoverflies include Melanostoma, Platycheirus, Chamaesyrphus and Neoascia. They mostly dwell in herbs and shrubby vegetation and are inconspicuous. Some can only be detected by sweeping the vegetation with a net. I do not know if they benefit from their body colouration or not. Bumblebee mimics. Some hoverflies are covered in long, dense hairs; these are the bumblebee mimics (photo 4 and 5). They have different colour patterns that resemble different species of bumblebees. Popular bumblebee models include Pyrobombus lapidarius (black with red tip), Pyrobombus hypnorum (pale-haired thorax, abdomen black with white tip) and the photo 4. The bumblebee mimic Eristalis intri- group containing Bombus terrestris, Bombus caria only deceives at first glance (M. van lucorum and Megabombus hortorum (photo 6) Veen). photo 3. Platycheirus tarsatus, one of the photo 5. The hairy Volucella bombylans is a small elongate hoverflies that have yellow bumblebee mimic, its plumata form resem- spots on the abdomen (M. van Veen). bles bumble bees like Bombus terrestris (M. van Veen). 8.

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