218 



almost abandoned. A light soil seems most liable to tlie 

 greatest havoc from the fly. 



The perfect insect looks somewhat like our common house- 

 fly, a little smaller, being about a quarter of an inch long, 

 of a pale-ash color, with black bristles thinly scattered over 

 its body, which has rust-colored markings upon it ; its wings 

 are tinged with yellow and buff near the shoulders. 



The female-fly deposits her eggs upon the leaves of the 

 plant close to the earth ; or more probably peirces the plant 

 and inserts them within the coats of the tender bulb. But 

 however this may be, it is certain that upon hatching the 

 larvge soon find their way to the heart of the onion and 

 cause its speedy 'death. 



After eating for about a fortnight's time, they arrive at 

 maturity, and undergo their transformation within the bulb, 

 issuing forth at the expiration of about two weeks' more, a 

 perfect insect, the whole process of these several changes 

 being so rapid, that it is computed, two or three generations, 

 may succeed each other in a single summer, as evinced by 

 the different sized maggots found in the same individual 

 onion. The latest l)roods hybcrnate in the pupa-state, 

 ready for a perfect life on the return of Spring. 



Your Committee do not speak conclusively from personal 

 observations made by themselves as would be requisite, had 

 they sufficient time for patient and careful scrutiny ; and in 

 absence of this and similar management, have availed them- 

 selves of the experience of others. They have consulted 

 two papers upon the general subject l\y I. 0. Westwood, 

 Esq., Secretary of the London Entomological Society ; to be 

 found in the Seventh Yolumc of the Magazine of Natural 

 History for the year 1834, and in the Seventh Yolume of 

 the Gardener's Magazine (Loudon) in which are figures of 

 the insect in its various stages of development. It would 

 be essential to study the minutest characteristics of our fly 

 with that above described, to identify it as the same : but the 

 habits and results seem to be of about the like destructive 

 and pernicious kinds. 



In a treatise on insects allied to the onion fly reported to 

 the Prussian Horticultural Society in the year 1830, Bur- 

 gomeister Borggrave of Bevingen, recommends from his own 

 experience the mixing of charcoal powder Avitli the surface 

 soil of the beds as a prevention to the ravages. 



M. Bouche suggested the plan of strewing powdered char- 



