THE WHEAT MIDGE. 91 



to a place of security. (Asa Fitch Rural New Yorker, Jan- 

 uary, 1856.) 



154. We may form some conception of the innumerable mul- 

 titudes of these insects which accumulate among the screenings 

 of infested wheat by attempting to estimate the number which are 

 annually swept out of barns in those districts where they abound. 

 Mr. Dawson relates in his * contributions towards the improve- 

 ment of Agriculture,' that a friend informed him that not less 

 than four bushels of larvae had been obtained from the wheat of 

 eight acres. After making a large deduction for dust this quan- 

 tity must have contained about 150 millions of these insects. 



155. It thus appears that these differences in the habits of 

 individuals hatched and so far matured in the same field are de- 

 pendent upon atmospherical conditions. Some of the full grown 

 maggots leave the grain at the close of a shower, or heavy dew, 

 and wriggle down the wet straw to the earth. Others which are 

 later in arriving at maturity, or in finding suitable weather for 

 making their descent to the earth, are carried during harvest 

 with the grain into the barn, and become subject to the singular 

 condition or state described in paragraph 153. 



156. Some very excellent observations on the habits of this 

 insect have been made by Mr. Principal Dawson, of McGill Col- 

 lege, Montreal, of which a record may be found in a work by 

 that gentleman before noticed, entitled, " Scientific contributions 

 towards the improvement of Agriculture in Nova Scotia." The 

 following are the observations referred to : 



" I procured a quantity of the larvae, full grown and in that 

 motionless and torpid state in which they usually appear when 

 the grain is ripe. A portion of these larvae were placed on the 

 surface of moist soil in a flower pot. In the course of two days, 

 the greater number of them had descended into the ground, pre- 

 viously casting their skins which remained at the surface (p. 157.) 



