12 



THE HESSIAN-FLY. 



crn states this insect is double brooded, and hibernates in 

 the flax-seed stage in \vinter-wheat, Yolunteer-wheat and in 

 other plants including, possibly, some of the larger grasses. 

 But this is their habit only in the south: here the insect 

 must lead a different sort of life, for instead of being double- 

 brooded it is single-brooded. This could be expected from the 

 conditions prevailing in the greater portion of our state, 

 but we have had no proofs thus far. Of all the infested 



stalks gathered as soon 

 as the injury became 

 visible, not a single 

 Hessian-fly has issued^ 

 and numerous puparia 

 (the flax-seed stage) 

 are still unchanged in 

 the breeding-cages. 

 This assuredly seems to 

 indicate that the flies 

 do not issue during the 

 autumn, as they do fur- 

 ther south, but remain in the culm until spring. Another 

 proof, though not a safe one to depend upon, is the fact that 

 no larvse or puparia could be found in the volunteer plants 

 of wheat growing near fields that had been badl}^ infested. 

 The many puparia kept in properly constructed breeding- 

 cages gave forth, however, 

 very large numbers of para- 

 sites. Three different species 

 were raised, and in such 

 numbers that in some cases 

 nearly all the Hessian-flies 

 had been destroj^ed in the 



puparia. Two of the para- y if \^ IW u "i 



sites are shown in the illus- 

 tration. Fig. 4 represents a 

 female of the most common 



Fig. 5. — Male of Eiipelmus aUynii 

 parasite {Mei'!.-<U-< de-'<tl'l(Cfor French. Enlarged. Original. 



Sa\') and fig. 5 tho: meiXt oi {Eupelinus all ynii Trench). The 

 female of the latter occurs both with and without wings. 



Fig. 4 — Female of JVier;si/s destructor Say. 

 Enlarged. Original. 



