that date from the same field as the foregoing. These were 
necessarily of the first spring generation, since, as noted above, 
those which had hibernated had ceased rendering the imago 
three weeks before, and the second generation of imagos did 
not begin to appear until a week later than the date of this 
collection. 
These flaxseeds were placed May 27 in a cage of young 
wheat grown in the enclosure (sown March 1), and the next day 
male and female flies were seen on the wing. May 31 an abun¬ 
dance of imagos were out, and again June 4, 9, and 14, but no 
further observations were recorded until June 26, when this 
wheat was overhauled and found to contain flaxseeds in nearly 
every stalk, except in now and then a green one where' the in¬ 
sect was still a larva, fully grown. 
It is specially to be noted that this wheat had done very 
badly, having been sown too thick and grown so slender in con¬ 
sequence that it soon fell down, and having suffered greatly from 
a peculiar fungus attack. It was also overstocked with flies, 
and rapidly killed, and it is not strange, therefore, that the flax¬ 
seeds of this second spring brood were all very small. 
On the 27th June wheat was sowed in still another cage, and 
in this the above flaxseeds were placed the same day. August 
15 and September 8 puparia were opened and found with living 
larvae still unchanged, but as the June wheat was now all dead 
from plant-louse attack, more was sown September 9. On the 
20th September a female appeared in the cage, and others were 
seen September 21, 22, and 23, eggs being laid September 22. 
From these insects larvae and flaxseeds resulted, and in this 
latter stage these flies are now passing the winter. No attempt 
was made this fall to separate the two autumnal generations 
previously recognized. 
The experiment just described clearly establishes the occur¬ 
rence of a second spring brood, and also of a period of summer 
rest or dormancy in the puparium, extending in this instance 
over approximately three months, or, more precisely, at least 
from June 26, when puparia were fully^ formed, to September 8, 
when larvae not yet pupated were found within the puparia. 
This period was probably, however, excessively long, as the 
formation of the puparia was apparently hastened in June by 
the defective food supply, and actual pupation was also 
clearly delayed in September by the dwarfed and feeble condi¬ 
tion of the larvae. Consistently with this I shall presently show 
from other observations that imagos may appear as early as 
the last week in August,—nearly a month, that is, in advance 
of these. 
I further derived from the following additional experiment 
ocular demonstration of the fact that the second spring gene¬ 
ration was only a partial one, and that not all the puparia of 
the first yielded the imago before harvest. 
