470 Wisconsin Academy of Sciences, Arts, and Letters. 
mum was found at the Maple Bluff station, the latter being almost 
twice as great as the former. The samples from West Bay and 
from the Center gave an average of 566 individuals per square 
meter, while those at station II numbered 549. 
There was a marked difference in the size of these larvae, and 
they were separated into three different classes on the basis of size. 
In 219 samples those larvae were recorded as small which did not 
exceed 12 millimeters in length; from this length up to about 18 
millimeters they were designated as medium, and those 20 milli¬ 
meters or more in length were called large. The largest larvae 
noted in this region of the lake were about 27 millimeters in length. 
The results of these enumerations for the various stations are 
shown in the second part of table 6. Station II yielded the largest 
average number of small individuals, and the Maple Bluff station 
ranked first in both medium and large sizes. Of the total num¬ 
ber of Chironomus larvae obtained at the five stations, the small 
individuals constituted 56 per cent., the medium size 31 per cent., 
and the large 13 per cent. Thus, the small ones were a little more 
than four times as numerous as the large ones, but less than twice 
as abundant as the medium size. 
The various sizes of this chironomid larva were found during all 
seasons of the year. Pupae were most abundant in May and early 
June, and again in the latter half of October, the maximum num¬ 
ber being found during the latter month. This indicates that these 
two periods are the chief ones for transformation, but pupation also 
takes place between June and October so that eggs are constantly 
being deposited during this interval of time. The eggs deposited 
by the adults which emerge in late October and early November 
give rise to a brood of young which flourishes during the winter 
months. The annual distribution of the different sizes is shown in 
table 7. The small ones were much more abundant in 1917 than 
in 1918, but, up to June, the medium and large sizes were more 
numerous in 1918 than in 1917. 
Average specimens of the three different sizes were picked out 
and their weights were determined; the results are shown in table 
8. The large individuals were from 23 millimeters to 25 millime¬ 
ters long, the medium ones from 14 millimeters to 16 millimeters, 
and the small ones from 8 millimeters to 10 millimeters. The live 
weight of the large specimens was a little less than five times as 
much as that of the medium ones, while the medium ones weighed 
