Xanthogramma citrofasciatum

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: Xanthogramma citrofasciatum.

English Name: None. A hoverfly Syrphidae.

French Name: Une syrphe, sans nom commun.

5 Key Characters:

• strong lemon yellow stripes down the sides of the thorax.
• long narrow lemon yellow wedge shaped triangles on the second abdominal segment.
• wings faintly enfuscated (as if they are tinged with brown).
• entirely orange legs.
• medium sized (11 - 15 mm long).

Lookalikes: The rumour in taxonomic circles is that X. citrofasciatum is likely to actually be a species complex of two separate species, but until such time as this is announced officially, the only confusion should be with the X. pedissequum group. X. pedissequum was also until recently thought to be a single species, but it is now known to be three - X. pedissequum, X. dives and X. stackelbergi. These three species all have broader yellow triangles on abdominal segment 2, clearly dark hind legs from just above the 'knee' down and more darkly shadowed wings. By far the easiest of these characters to judge in the field and from photos is the leg colour. The X. pedissequum group is more abundant than X. citrofasciatum, but still not common.

Habitat: Grasslands with many Lasius spp nest mounds (especially Yellow Meadow Ant L. flavus), such as meadows, large gardens, pasture and woodland rides, especially if well drained, dry and on chalk or limestone. The hoverfly larvae seem to live in the ant nests, feeding on the root aphids that the ants 'milk' for honeydew.

Flight Period: April-May-June-July-August-September.

Status: Scarce. We see maybe one or two a year near Preuilly-sur-Claise. A lowland species.

Photographed by Loire Valley Nature: