1907 



ENTOMOLOGICAL SOCIETY. 



103 



be a hoss-fly,* and the habits of even this depreciated "hoss-fly" are so re- 

 markable and its life-history is so strange, that, duly observed, they can- 

 not fail to intercvst. 



Undoubtedly many of the two-winged flies cause annoyance, both to 

 man and beast; some are highly destructive to our food-supplies; some, on 

 the other hand, are useful in keeping down the numbers of other insects, 

 and others again, in consuming animal and vegetable substances that would 

 cause harmful exhalations. 



I shall endeavour to guard against wearying my readers with minute 

 descriptions of many species. I hope to kindle an interest in th*e Diptera 

 by telling of peculiarities in the structure and habits of some of the more 

 remarkable of the kinds that have come under my notice. 



The first family ^n Osten Sacken's list is the Cecidomyiidoc a very im- 

 portant group of insects. In it come two of the worst insect pests that have 

 troubled the Agriculturist, viz., the Hessian Fly (Fig. 33), Cecidomyia de- 

 structor, Say, and the Wheat Midge, Diplosis tritici, Kirby (Figs. 34 and 

 '^5). 



/ * \ 



Fig. 33.— Hessian Fly 

 — greatly magnified. 



Fig. 34. — Wheat Midge — natural 

 size shewn below. 



Fig. 35.— Wheat Kernel 

 attacked by Midge. 



Fig. 36.— Willow-gall iNlidge- « the 

 iiy, much enlarged, 6 antenna 

 highly magnified. 



Fig. 37. — Diplosis grassator — 1 larva, 2 pupa, 3 fly, 

 side view, 4 fly, under side (original). • 



Of C. destructor, two broods appear in the year — one in May, the other 

 in September. Each female fly lays about 30 eggs, on the blades of wheat, 

 or of some other kind of grass. The eggs are minute, cylindrical, red points, 



*"And you're a doctor, I reckon, though you're only a cow-doctor — for a fly's a 

 fly, though it may be a hoss-fly," eoncluded Mr. Macey, wondering a little at his own 

 "cuteness." — Silas Marner, ch VII 



