84 THE SCOTTISH NATURALIST 



and produce a batch of eggs which would be fertilised by the 

 sperms received in autumn, and maintained alive through 

 the winter in the receptacula seminis. In this respect 

 LimnopJiora septeninotata agrees with the Common Gnat, 

 Ctdex pipietis (and no doubt with other Diptera which 

 hibernate as imagos), specimens of which collected in late 

 autumn or winter hibernating in cellars or outhouses are 

 invariably females. I have examined during class-work, and 

 for other purposes, some hundreds of such hibernating gnats, 

 and have found, without exception, that their receptacula 

 seminis contained living spermatozoa. 



Plague of Plies in a Renfrewshire house. — The paragraph 

 in the editorial of the March number of the Scottish Naturalist 

 concerning the "plague of flies," much interests me. ^^'e lived for 

 seven years in a house at Caldwell (Renfrewshire), known as " Hall 

 of Caldwell." This was an old-fashioned house facing N.E. The 

 principal rooms went from the front to the back, with a window in 

 each wall directly opposite to each other. The drawing-room was 

 above the kitchen. In the autumns of 1906, 1907, and 1908 we 

 had a plague of flies there. There were a few on the kitchen 

 window facing N.E. In the drawing-room above, however, on the 

 corresponding window (viz. N.E.) the flies were in thousands — so 

 black that it was difficult to see through. They covered the wood- 

 work and roof above, anl swarmed in behind the wooden shutters. 

 There were a few Common House flies, but the multitude were of 

 a fly about one-third smaller than the Common House-fly, and black. 

 I got a tin of " Keating's '"' and dusted it on them and on the 

 window-sill — everywhere that Keating's would lie. This quickly 

 killed them off — they were then swept up — not a fly left. Next 

 day they were as bad as ever. This usually went on for a week or 

 ten days. It should be noted that this point applies to each year. 

 Although there was a window in the same room facing S.W., very 

 few even went near it. In both the apartments they kept to the 

 windows facing N.E. No other rooms in the house were visited, — 

 T. Thornton Mackeith, Kilmacolm. 



