256 INSECT TRANSFORMATIONS. 



rounded at the tip, and fringed with hairs.* The 

 female is furnished with a retractile ovipositor, four 

 times as long as her body, and as fine as a hair, for 

 depositing her eggs, Nvhich she does in the glumes of 

 the florets of the grain. The following account of its 

 proceedings is given by Mr. ShirefF, an intelligent 

 farmer of East Lothian. 



"Wheat-flies," he says, "were first observed here 

 this season on the evening of the 21st of June, and, 

 from the vast number seen, it is probable a few of 

 them may have been in existence some days previous. 

 The eggs were visible on the 23rd, the larvae on the 

 30th of that month, and the pupae on the 29th of 

 July. 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 (Tnti- 

 cum repens). 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 

 appear 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 shim that which is 

 deficient in foliage. 



" The flies almost invariably preferred the ears 

 emerging from the vagina to those further 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 

 * Linn. Trans., iii. 213 ; iv. 234-240 : v. 96. 



