480 Insect Pests. 



THE GRAPE FRUIT FLY. 



{Di'osopliila incldihixjiistcr. ^Ig.) 



This fly, well known on the Continent and in America, is fairly 

 common in parts of Britain. It was first recorded as a vine pest in 

 this country by Austen (1), but there are records of similar attacks 

 in America. 



Forbes (2) refers to the damage done to the grape crop at Moline, 

 Illinois. The damage recorded by Austen w^as done to a crop of 

 Lady Downe's seedling at Thongsbridge, near Huddersfield. This 

 was the only variety attacked. Several of the maggots were found 

 in each berry. Its usual food seems to be decayed or decaying fruit 

 and other vegetable matter, and it also l_)reeds in fermenting liquids. 



Williston (3) refers to it appearing in "clouds" around heaps of 

 cider refuse, and states that it never attacks sound fruit. 



On the other hand, Comstock (4) refers to it as the " Vine-loving 

 Pomace Fly," and quotes Mr. AV. L. Devereau, of Clyde, New York, 

 as follows : — " The larvpe of this fly completely eat out the inside of 

 grapes which, while hanging on the vines, have first been picked open 

 by birds. The decaying juices running out on the other berries spread 

 decay and thus give more foothold for the larva\ Indeed the larvre 

 bore from one grape to another, while the imagines are constantly, 

 by eggs, putting in new colonies until the cluster is nearly or quite 

 destroyed, nothing remaining but the empty grape skins." 



Melichar (6) records it " in countless myriads in an open barrel 

 half full of rotten and fermenting fruit." 



Howard (10) has bred it from human excrement. 



Its wide distribution including, besides America and Europe, 

 Western Australia, South Africa, Cuba, points to its being spread 

 artificially. Sucli we can see may readily happen in cargoes of 

 unsound fruit. 



Lifp:-IIist()i;y. 



This has been \vorked out by Howard (5). The fly measures 

 about 2 mm. in length. The head, thorax and base of the abdomen 

 are dingy yellow. The abdomen is banded with brown at the base 

 and the apex l)lack. The male can at once be told by the presence 

 of a small black comb-like structure on the inner side of the first 

 front tarsi. 



They lay their eggs on any decaying or fermenting matter, and 

 the larvi^e hatch and develop very rapidly — a generation may develop 



