Apr. is, 1914 
Corn-Leaf Blotch Miner 
23 
LENGTH OF PUPAL, STAGE 
The pupal stage varies from 14 days in warm weather to 22 days in 
spring and fall. In the late summer of 1912 there were some puparia 
that did not disclose adults, and upon examination they were found to 
be in good condition in November. These puparia were kept indoors 
and disclosed adults in January and February. They were of the genera¬ 
tion that pupated from the middle to the latter part of August. This 
would seem to indicate that some go into hibernation rather early in the 
fall. 
eife and habits of the aduets 
The flies begin to issue during the latter part of May. The males will 
not live more than three or four days in confinement, whereas the females 
will easily live two weeks when the weather is not too hot. It will thus 
be readily seen why the generations overlap so completely, since the 
progeny of one individual may be in the pupal stage before she ceases 
oviposition. The males apparently do not feed, though the females do 
considerable feeding, as evidenced by the punctures in the leaves shown 
in Plate I, figure 4. Both males and females, however, appear to be fond 
of water and seem particularly thirsty soon after issuing. In midsummer 
the adults appear to be most active in early forenoon and late afternoon. 
In midday they appear to seek shelter on the underside of leaves. 
NUMBER OF EGGS DEPOSITED BY ONE INDIVIDUAE 
The female flies begin oviposition in 5 to 10 days after emergence, if 
males be present; otherwise they will refuse to oviposit. There are no 
very complete observations on egg laying. Several individuals were 
observed, but for various reasons the records are not complete for their 
whole life. They have been found to deposit from 30 to 60 eggs, but 
will doubtless deposit more than this throughout the whole period. 
Dissections give no satisfactory clue to the number of eggs that may be 
deposited. The species will apparently breed as freely in confinement as 
out of doors. 
NUMBER OF GENERATIONS 
It is almost impossible to get a clue to the number of generations by 
making observations in the field, since they overlap so completely. 
After the first generation, if the insects are at all abundant, eggs, larvae, 
and adults can be found in the field simultaneously throughout the 
remainder of the year. Therefore, early in the spring of 1912 a series of 
rearings was begun in confinement, and this series was continued until 
freezes killed off the vegetation in the fall. It was found that there 
were four complete generations and a partial fifth. It is possible that 
the insects may breed more rapidly in the open fields and that if they 
could be readily followed it would be found that there are five generations. 
