474 Wisconsin Academy of Sciences, Arts, and Letters. 
II on December 21, 1917; the smallest number was also noted at 
this station, namely, 295 larvae per square meter, found on August 
2, 1917. 
The curve shown as a broken line in figure 1 represents the aver¬ 
ages for the five stations. This curve is interrupted during the 
winter each year because station II was the only one visited regu¬ 
larly during this season of the year. The monthly averages for the 
five stations are larger than those of station II during the period 
from July to October, but they are smaller than the latter in No¬ 
vember and in December, and also from April to June. In Decem¬ 
ber, 1916, however, the two averages were substantially the same. 
The maximum differences between the two averages were obtained 
in April and in December, 1917; on the former date the average 
for the five stations was more than 22 per cent, below that of sta¬ 
tion II, while on the latter date the difference was a little more 
than 25 per cent, in favor of station II. 
Small swarms of adults appear in May and in early June, but 
the great flights do not begin until late June or early July. The 
most vigorous period of transformation from larvae to adults lasts 
from early July to about the middle of August. During this in¬ 
terval of time several great waves of adults appear; as a result of 
the rapid pupation at this time the larvae decline to the minimum 
number of the year in early August. In late August and early 
September there is a slackening in the pupation, and correlaated 
with this is an increase in the number of larvae. As autumn ad¬ 
vances pupation becomes less and less frequent; this decline in 
transformation, together with the hatching of the vast numbers of 
eggs deposited by the later broods, results in a rapid rise in the 
number of larvae. This rapid increase begins in late September 
and continues until November or December. (See fig. 1.) 
Between June, 1916, and April, 1917, more than fourteen thou¬ 
sand Corethra larvae were sorted out and dried for the purpose of 
making chemical analyses of them. The average amount of dry 
matter in each individual was 0.251 milligram. In addition to 
this, eleven other lots, consisting of 100 to 300 larvae each, were 
weighed, and their dry weight ranged from a maximum of 0.311 
milligram per individual in June to a minimum of 0.182 milligram 
in early September. The results of these weighings are shown in 
table 12. The higher average of dry matter in the June material 
was probably due to a larger proportion of chitin in the larvae just 
