178 [August, 



AN EPIDEMIC AMONGST MELANOSTOMA SCALAR E, F., CAUSED 



BY A FUNGUS. 



BY RALPH C. BRADLEY. 



Whilst collecting in Blackroot Bog, Sutton, on June IGtli I came 

 across an extraordinary phenomenon. For a space o£ about a dozen 

 square yards the flowering stems of a grass (apparently Glyceria 

 ftuitans) were covered with a large number of dead Melanostoina 

 scalare, F. {Syrphidce) , whose bodies were very much distended by a 

 fungoid growth, similar to that seen on the house fly in the autumn. 

 Some stems bore thirty to forty specimens, and fresh victims were 

 constantly being added, about 90 per cent, of the whole being females. 



Two days later, paying a second visit, I found the same process 

 going on, and also two flowering stems of dock covered with the dead 

 bodies in a similar manner. 



It seems improbable that sucking the juices of the flowers could 

 produce this fungoid condition, but certainly the flies were to be found 

 only on the flowering parts of the stems, and not on any leaves or 

 herbage. 



Why M. scalare should be the only species attracted to the stems 

 and attacked in this manner is very curious, as swarms of other insects 

 were flying about, but did not seem to be tempted to join them in the 

 least. Perhaps some other entomologists have met with a similar 

 experience, and can throw some light upon the matter. 



Sutton Coldfielcl: 



June, 1895. 



[With this communication Mr. Bradley obligingly forwarded a 

 supply of panicles of the grass crowded with the dead bodies of the 

 fly, and presenting a most singular appearance. Some of the flies 

 have been examined by Mr. G. Massee, F.L.S., of Kew, and he iden- 

 tifies the fungus as JEvqjiisa conglomcrata, Thaxter, a rare sj^ecies in 

 North America and the Continent of Europe, and never before observed 

 in Britain. It is noticed as chiefly attacking larvae and imagos of 

 TipuJidce. Possibly the germs of the disease may have been acquired 

 by the larva) of the Melanostoma in the first instance : but how ?. I 

 would be inclined to doubt any direct connection between the grass 

 and the disease ; but the flowers of Glyceria are well known to be very 

 attractive to insects, and the fungus may have developed very rapidly 

 when the flies were feasting. — 11. McLachlan]. 



