HESSIAN FLY. 
39 
bunch of rank-growing leaves. In any case the darker colour of the 
leaf and the absence of the central leaf, together with the bunchy 
appearance of the part affected, will readily distinguish a fly-infested 
plant from one not injured. The yellow colour of some leaves is 
seldom observed at this season of the year on fly-infested plants.” 
Dr. Lindeman states:—“At first scarcely any stoppage in the 
rate of growth is to be observed, as is the case in a long continuation 
of drought, but soon the young plants begin to wither and at last die 
away ; also the plant leaves commonly all wither at the same time, with 
but very little change of their green colour. If we examine the dead 
plants closely, we find that neither leaves nor stem are gnawed, that the 
root is healthy, regularly developed, and branching, and that there are 
no traces of the characteristics of insect-feeding known as worm meal. 
“The plant appears killed as if by being simply dried up. Low 
down by the root it is commonly swollen, and here, in the axil of the 
leaf, is either the maggot of the Hessian Fly, or still more frequently 
the puparium itself, in appearance a brown elliptical shining body 
extraordinarily like a flax-seed.* 
The above descriptions may serve as guides as to existence of 
winter infestation, or conditions where it has been. 
* Die Hessenfliege (Cecidomyia destructor ), Say, in Eussland, von Dr. K. Lind 
man, Moscow, 1887. (Eng. Trans. M.S., by Georgiana E. Ormerod, pp. 22, 23.) 
