Glass-winged Syrphus Hover Fly - Syrphus vitripennis

To identify flies to family level use a simple wing venation key such as A Key to the Families of British Diptera, an AIDGAP by D. Unwin, published by the FSC and available as a free download (scroll down to the titles list) or a more detailed key which includes many physical characters such as The European Families of the Diptera by P. Oosterbroek. The expert dipterists on the DipteraInfo forum are also very happy to identify, often to species level, from good photographs.

Scientific Name: Syrphus vitripennis (Syrphidae Syrphini).


English Name: Glass-winged Syrphus; Lesser Banded Hover Fly (Hover fly family, Syrphini tribe).


French Name: 

5 Key Characters:

• scutellum (the small semi-circular part between the thorax and the abdomen) tawny yellowish.
• strong yellow 'moustache' bands on the abdomen.
• eyes hairless.
• hind femur (thigh) is black for most of its length from the base (females only).
• rather small for a Syrphus.
  

Lookalikes: Often mistaken for other Syrphus spp or Eupeodes spp (eg Migrant Hover Fly E. corollae). Could also be mistaken for Eriozona erratica or Parasyrphus spp. To separate Syrphus from other genera it is necessary to stretch out the wing and check for hairs along the edge of the squama (part of the wing which forms a sort of flap at the base). Syrphus have this fringe of hairs, other genera do not. They are visible using a loupe, but you need to get the angle and light just right. An easier way to distinguish Syrphus is to check underneath the abdomen (the sternites). Syrphus is yellow, and if there are black spots they are in the middle and do not reach the edges (other genera are extensively black underneath). Syrphus is slightly bigger than Parasyrphus or Eupeodes. The hind tibia on Syrphus is always at least partly yellow (other genera are often all black).

It is very easy to mistake this species for the other very similar bare eyed Common Banded Hover Fly S. ribesii or S. rectus. Females can be distinguished because S. vitripennis has black on the hind femur, the other two have entirely yellow hind femora. Males need to be checked for the presence of black hairs in the yellow part of the hind femur. S. vitripennis does not have the black hairs, but they can be very difficult to see, requiring just the right light and angle. In common with many flies, males and females can be distinguished by whether the eyes touch (males) or are divided (females).

Habitat: Found in most habitats. The larvae predate aphids and overwinter in leaf litter beneath aphid infested trees, especially sycamores.


Flight Period: March-April-May-June-July-August-September-October-November.


Status: Common and widespread.


Photographed by Loire Valley Nature: