confusion of belated imagos from them with those to emerge 
from the freshly formed flaxseeds of the spring generation. 
From these latter the first winged flies appeared May 28, in 
the wheat first stocked, and May 30 I ascertained that all the 
larvae in both enclosures had changed to puparia, May 31 
imagos appeared also in the second plot—just eight weeks from | 
the time of the appearance in this plot of the first imagos of 
the brood preceding. This is longer by one or two weeks than 
the time heretofore assigned to the life of a generation of the 
Hessian fly:* a fact possibly accounted for in part by the rel¬ 
atively scattered appearance of the first flies in these cages, 
and the consequent possibility that the eggs of these short-lived 
insects would for a time be sterile for lack of fertilization. 
New plots of transplanted wheat were now ready out of doors 
for a transfer of the experiment, and the flaxseeds of this first 
complete spring generation, described above, Avere collected from 
the wheat in which they had formed and placed in paper boxes 
among this new Avheat. The escape of the imagos, already 
begun in the first cages, continued also in these, and flies of 
both sexes Avere seen on the Aving or resting on the coA^er of 
the cage from June 8 to 14. The Avheat in these plots nearly 
all succumbed about June 20 to an attack by the grain Aphis, 
brought in Avith it from the field (where this insect Avas becom¬ 
ing A r ery abundant), and June 26 the remnant Avas overhauled 
for Hessian flies, the Avheat remaining being now nearly all 
ripe. An average of twelve per cent, of the stems of both these 
lots Avas found to contain the fly, hoav all in the flaxseed state, 
necessarily, it aa ill be seen, of the second generation subsequent 
to those hibernating in the Scott county field, with Avhich the 
experiment began. 
The Avheat plants containing them varied from two inches to 
three feet in length. About three fourths of the puparia Avere 
lodged just above the lowest joint, and the remainder of them 
below that joint, with the rare exception of one higher up— 
aboA^e the second or even, in one case, aboAm the third joint of 
the stem. 
• The next day, June 27, the flaxseeds of this second spring 
generation thus collected Avere placed in still other cages, out of 
doors, in which wheat \A’as sown at the time, AA T ith the intention 
of folloAving their midsummer history. Owing to my absence 
from the State during the months of July and August I can¬ 
not report precisely on this midsummer Avork. Flaxseeds AA 7 ere 
opened August 15 and found to contain still living larvae, but 
the wheat died from plant-louse attack, and nothing further 
AA T as recorded from this lot. 
The above experiment AA’as paralleled and verified in its most 
essential points by another, begun May 21 with a second very 
large lot of full grown laiwme and recent flaxseeds collected at 
* See Fifteenth Report from this office, p. 2G. 
