116 , TURNIP. 



April of the past season, and as the species was not known to the 

 observers, specimens were sent to myself for identification, which 

 proved to be of the T. re(jelationis, and, as the matter is of some 

 interest, I give a part of my reply to the Editor of the ' Banffshire 

 Journal ' (see number for May 8th) : — 



" With regard to the species, this on the first glance appeared to 

 be the very common Trichocera hiemalis, well known as frequenting 

 rotten Turnips, of which an excellent description and figure is given in 

 Curtis's 'Farm Insects,' p. 137. 



" On turning, however, to the long and minute descriptions of 

 different species of Trichocera given in the ' Fauna Austriaca ' (Diptera) 

 of J. E. Schiner, vol. ii. pp. 547, 548, I found it noted that the 

 T. hiemalis is like another species of Trichocera, namely, T. regelationis, 

 in colouring, but is distinguishable from it by the wings of the hiemalis 

 being quite clear and transparent, whereas the wings of the rajelationis 

 have a slight darkish spot on the little cross-veins. 



"This small greyish spot I found was present; but as mere 

 matters of colouring are sometimes variable, I submitted my doubt 

 (together with your specimens) to Mr. B. H. Meade, of Bradford, one 

 of our chief authorities on the Diptera, and I have heard from him in 

 reply, as follows : — 



*" The flies that you sent me are the Trichocera re(jelationis ; the 

 wings of T. hiemalis are quite clear without any spot. These species 

 are sometimes very difficult to determine, for the nebulous patch upon 

 the vein is sometimes much more distinct than at others.' " 



In regard to method of life of these gnats, it has so long been 

 recorded on trustworthy authority that they are an nifestation of 

 rotten vegetables, that there does not appear any openiog for doubt, 

 and I believe that the matter could not be better put than in the 

 following few words of Prof. M. C. Potter, of the Durham College of 

 Science, when consulted regarding this infestation: — "There can be 

 no doubt that its grubs merely live in the rotten Turnips, acting as 

 scavengers, and are in no way responsible for the rottenness; but that 

 they may aid in the work of destruction is probable, for flies in various 

 ways disseminate the spores and reproductive bodies of fungi." 



And the following sentence from the same letter by Prof. Potter is 

 well worth attention : — " The best way to combat the insect and 

 fungus infestations is to thoroughly destroy all rotten and diseased 

 plants. To leave them lying about, or to throw them to manure-heaps, 

 is merely to extend their ravages; and farmers will find it more 

 economical to destroy the germs of disease in this manner, than to 

 have a large part of their crops destroyed, or to spend money in 

 remedies which have a very uncertain effect." * 



* From ' Banffshire Journal ' for May 22nd, 1894. 



