2J2 



CHANCEY JUDAY. 



lake. The results obtained at only one of these stations, desig- 

 nated as Station II., are considered here, however, because the 

 other four were not visited regularly during the winter months. 

 From April to June inclusive, the number of larvae found at Sta- 

 tion II. was from 10 per cent, to 20 per cent, larger than the gen- 

 eral average of the five stations during these months, but in 

 August the general average was larger than the numbers at Sta- 

 tion II. In the six sets of averages obtained for the last three 

 months of the year in 1916 and 1917, three of the averages for 

 Station II. were larger than the corresponding averages of the 

 five stations and three were smaller. Thus, the numbers ob- 

 tained at Station II. were somewhat larger than the general aver- 

 age for the deeper part of the lake as a whole during the first 

 half of the year, but they were somewhat smaller from July to 

 September and substantially the same from October to De- 

 cember. 



NUMERICAL RESULTS. 



The average number of Corethra larva? per square meter of 

 bottom is shown for the different months of the year in Table I. 

 Large numbers of these larvae live over winter ; in fact they are 



TABLE I. 



THE NUMBER OF CORETHRA LARVAE PER SQUARE METER OBTAINED FROM THE 

 MUD ix THE DAYTIME AT STATION II. DURING THE DIFFERENT MONTHS 



OF THE YEAR. 



In all months except January and February the numbers represent averages 

 of two to nine samples. 



more numerous from November to April than at any other time 

 of the year. During this interval the numbers range from ap- 

 proximately 18,000 to 30,000 individuals per square meter. At 



