RAVAGES OF MAGGOTS. 251 



The eggs were visible on the 23cl, the larvse on the 

 tiOth of that month, and the pupce on the 29th of 

 Julj, The flies were observed depositing eggs on 

 the 28th, and finally disappeared on the 30th July; 

 thus having existed throughout a period of thirty-nine 

 days. 



' The flies were observed to frequent the wheat- 

 plant, including the thick-rooted couch-grass ( Triti- 

 cum rcpens). They generally reposed on the lower 

 parts of the stems during the day, and became active 

 about sunset, except when the wind was high. I 

 have, however, seen them flying about on cloudy 

 mornings, till seven o'clock; and, upon one occasion, 

 witnessed them depositing their eggs, in a shaded 

 situation, at two in the afternoon. Their movements 

 ar)pear to be influenced by the rays of light, of which 

 they seem impatient, being active when the sun is 

 below or near the horizon; they frequent the most 

 umbrageous part of the crop, and shun that which is 

 deficient in foliage. 



' The flies almost invariably preferred the ears 

 emerging from the vagina to those farther advanced, 

 for depositing their eggs on; and as one side only 

 of the ear is exposed when the plant is in this stage 

 of growth, the other side generally remained unin- 

 jured. The fly deserted the fields as the crop ad- 

 vanced towards maturity, and were found longest 

 on the spring-sown portion of the crop. It seemed 

 to feed on the gum adhering to the newly emerged 

 ears; and as there is a great diversity in the time of 

 sowing wheat in this neighbourhood, and conse- 

 quently of the ears escaping from the vagina, I 

 attribute the unusual length of time it has existed 

 this season, to the supply of food thus gradually fur- 

 nished. 



^ The fly deposits its eggs with much intensity, 

 and may easily be taken when so employed. Upon 



VOL. VI. 22* 



