I30 



upper leaf. But it was not until the latter date that the flies had 

 migrated to the wheat fields in considerable numbers. It will be 

 noted that as the insect winters in the stubble of wheat, and that 

 as in this region one crop of wheat rareh' follows another, it is 

 necessary for the adults, when they emerge, to migrate a greater 

 or less distance in search of a wheat field, in which to oviposit. 

 We found that the female migrated to the wheat fields first ; but 

 they were soon followed by the males. 



The specimens which I reared in breeding-cages in which wheat 

 was growing laid their eggs at various distances from the ground. 

 Many observations, both in the Insectary and in the field, con- 

 vinced me that these insects oviposit anywhere along the larger 

 part of the stravv' where it is hollow ; but chJefly in the upper por- 

 tion. (See Table i.) In each case that I observed, the female 

 stood with her head towards the ground in the position indicated 

 in the Plate, at a and b. The making of the slit through the 

 straw, and the laying of the &<g% occupy about on.e minute of time. 

 The slit made by the insect's ovipositor is so small that it can be 

 detected only with difficulty. By carefully marking the point on 

 a straw, at which a female was seen to oviposit, and then examin- 

 ing this point with a microscope, I was enal)led to find the punc- 

 ture. It is about one one-hnndreth inch (J:(mm.) in length, 

 slightly enlarged at the upper end as shown in Fig. 2, a. The 

 ^Z?, i'5 pushed entirely through the wall of the straw and is left 

 adhering loo.sely to the inside. It is of a milky white color, one 

 twenty-fifth inch (i mm.) in length, and one seventy-fifth inch 

 {Yi mm.) in width at its widest place. It is oblong, and shghtly 

 curved, as .shown in Fig. 2, b. 



In our breeding-cages the females laid 

 many eggs in the same stalk. This 

 was to be expected, ov/ing to the large 

 number of insects confined with a small 

 amount of grain ; but I was surprised 

 to frequently observe a female lay an 

 eae and then move down the same 

 stalk two or three inches and repeat the 

 operation witliout an effort to seek a 

 fresh stalk. 



Although many eggs were laid in .some 

 of the stalks in our breeding cages, in no 

 instance did more than one larva become 





Fig. 2. — a, section of straw 

 showing form of slits made by 

 the ovipositor; b, ^%%, greatly 

 enlarged. 



