A PLAGUE OF HĂ–VER FLIES. by W .
T H O U G H normally little noticed by the general public, the firsi week of August, 1960, brought both press and broadcast comments on the sudden abundance of these " wasp-like-flies " at^East Coast towns.
In fact, a few species of hover flies including the easily recognised species Syrphus balteatus Degeer and Sphaerophoria scripta Linn., were unusually numerous by July 28th, and this population swelled during the next two weeks to a remarkable extent. On August 4th, I counted the insects impaled on my car radiator, to estimate roughly the ratios of species present in the plague. The battered bodies of Syrphus balteatus and of Sphaerophoria scripta, were easily recognisable, but to teil Syrphus corollae Fab. from S. Inniger Meig., and S. ribesii Linn, from 5. vitripennis Meig., was not so easy in their condition. My count was as follows :â€” Sphaerophoria scripta
S. corollae and S. luniger
S. ribesii and S. vitripennis
Scaeva pyrastri Linn.
Eristalis arbustorum Linn.
Syritta pipiens Linn.
V 152 flies
" Winged Ant "
Ot these insects, the 152 bracketed flies have all carnivorous larvae, feeding on greenfly and other aphids. It was noticeable that hover-flies with vegetarian or scavenging maggots were no commoner than usual. It would seem that these flies had migrated from the Continent, the more so since Mr. W. V. Burrell, flshing 4 miles off Aldeburgh at this time found swarms of such flies, and the next day found the sea littered with their bodies.