EXPEDIENCE OF PRACTICAL GROWERS. 



ai maturity, and change to the pupa state, fig 5, and 

 in from fifteen or twenty days more emerge the perfect 

 fly, fully prepared to accomplish their depredations by 

 depositing their eggs upon the more healthy plants. 

 A.S many as from one to five of the larvaB were fre- 

 uuently to be met with on a single plant. 



The perfect insect is about half the size of the com- 

 mon nouse-fiy, with a few thinly scattered hairs cover- 

 ing the surface of the body. It is of an ash-gray color, 

 the males being distinguished by a series of dark stripes 

 upon the back. The head is marked with a brownish 

 spot upon its apex. The wings are exceedingly trans- 

 parent, exhibiting beautiful iridescent reflections from 

 their surfaces, the shoulders of which are of an ochery- 

 brown color, and the veins of brownish yellow. 



This fly may not unfrequently be met with in the 

 spring of the year, basking in the sunshine about the 

 windows of the neighboring dwellings. And from the 

 circumstance of finding their larvae in the greatest pro- 

 fusion, committing their depredations in the middle and 

 latter parts of August, we are inclined to believe that 

 they pass through several generations in a season, and 

 that they probably make use of the seed of the plant, 

 on which to deposit the egg for the larvae of the en- 

 suing spring. If this be so, steeping the seeds in 

 brine, before sowing, we should suppose would be the 

 proper remedy ; if otherwise, the process will not mate- 

 rially affect their germination. They appear to show 

 a distinct predilection lor the white onion, in preference 

 to that of any other color. 



This insect it is exceedingly difficult to destroy. 

 Strewing the earth with ashes has proved of little 

 avail; powdered charcoal answers a much better pur- 

 pose, and is generally in use in this section of country, 

 but it should ouly be thrown over about two thirds of 

 the bed, so as to leave a portion of the plants for them 

 to resort to on being brought to the perfect state, and 

 driven from their original resting-place. When they 

 have been converted to the larva state and commenced 

 their depredations, these plants should be pulled up 

 and consumed by fire. 



It has been recommended to prepare the beds as 

 early in the spring as convenient, and suffer them to 

 remain eight or ten days for the noxious plants to 

 vegetate, then to cover them with straw to the depth 

 of ten inches, and burn them over ; after which, plant 

 the seeds for the ensuing crop immediately. This pro- 

 cess, it is stated, has proved perfectly successful in 

 driving away the insects and insuring good crops, and 

 in addition to this, has furnished a capital top-dressing 

 to the soil. Onion-beds prepared from the hearths 

 upon which charcoal has been burned, have likewise 

 been mentioned as producing the perfect vegetable, 

 entirely free from the attacks of the fly. 



Should the charcoal method here mentioned, be uni- 

 versally adopted, we have little doubt but that this 

 insect depredator will in a short time become greatly 

 reduced in number if not entirely destroyed, and afford 

 a much better chance for a more healthful crop of tho 

 onion plants hereafter. J. K, 



