How to tell a hoverfly apart from other flies?
Being a biologist I enjoy the burden of seeing deeper and further when taking walks into “the wild”, especially pertaining animals and plants. To an average person, a walk in the woods is usually just a walk with background noise and green plants, but to me, there are dozens of plant and animal species to observe and listen to. Average layman usually sees animals for what they appear to be, but upon closer inspections, they are often caught red tarsused (bio-joke™) faking someone else. This is often the case with hoverflies (scientifically they’re called Syprhidae). They have found a way to mimic poisonous insects like wasps, bees and bumblebees. Many hoverflies mimic colors and patterns, but some have taken a step (3 steps, having 6 pairs of legs?) further and can mimic behavior as well. However, if a person takes some time and observes these animals, they can be discerned from their poisonous counterparts with relative ease. If you don’t have your eye trained on hoverflies, here is one (but not the only) anatomical character (see Picture 1) that can aid identification, especially if you have a specimen pinned down or in a net. This family of flies has a vena spuria, a chitonous fold in the wing. While this is present in large majority of species, some genera have it reduced or lack it altogether. In that case, others characters must be taken into consideration as well. Other insects, as far as I know, lack this “vein” in its entirety. The biggest give away is hinted already in their name. They have a distinct pattern of flying - darting around with hovering between darts. Hovering is, however, not confined to this family (see Picture 2, a fly from family Bombyliidae). With spring arriving shortly, take a minute to observe these fascinating animals. For further reading, see Hoverflies of Northwestern Europe by M. P. van Veen. The hoverfly in this post is also pictures on the front page of this book. This is also a good start-up book for any dipterologists located in or near this region.
Picture 1 (Episyrphus balteatus, a cosmopolitan, appears to overwinter as imago and emerges early)
Picture 2 (a bombyliid photographed while hovering)
