200 Anyials Entomological Society of America [Vol. X, 



reaches 78°-80° F., mortality drops off. Slight recrudescence 

 may occur during May to October, i. e., when a fall in the mean 

 temperature occurs. It should be borne in mind, however, 

 that the single factor temperature is not the critical one; it is 

 rather the resultant humidity which counts. 



2. Poona City and Cantonments. — It is 80 miles from 

 Bombay, 2,000 ft. above sea level, and has a daily mean tem- 

 perature of from 70° to 80° F., with an average diurnal range 

 of 22.5° F. From May to October it is subjected to the S-W 

 monsoons, but the rainfall (March to June) is less than that of 

 Bombay. June is the hottest and dryest month, its daily 

 mean. temperature being from 83° to 90° F. In July the daily 

 mean is from 75° to 80° F., with S-W breezes. The winter 

 months have a daily mean of about 70° F., and an average 

 diurnal range of about 30° F. 



The plague epidemics occur between August and March. 

 The charts show that mortality increases rapidly as the humidity 

 recedes from its maximum crest. The period of high plague 

 mortality is relatively short, dropping off as soon as the humidity 

 rises. 



3. Nagpur City. — It is in the Central Province and resem- 

 bles much Poona, excepting that its mean temperature is 

 slightly higher. Its hot season is from March to June, the 

 mean temperature being from 85° to 95° F. During July to 

 September the temperature is a little over 80° F., while during 

 the cold months (November to February) it is from 70° to 75° F. 

 The rainfall occurs from June to September, and ranges from 

 40 to 60 inches. 



Plague epidemics were most favorable from November to 

 March, and the charts again show plague mortality lowest when 

 humidity was highest. 



4. Belgaim City. — This is in the extreme south of Bombay 

 Province, 2,500 ft. above sea level, and 75 miles inland from the 

 West coast of India. The mean temperature from June to 

 February is from 70° to 75° F., with an average diurnal range 

 of 20° F. March to May is the hot period, the daily mean 

 being about 80° F. The rains occur mostly from June to Octo- 

 ber, and amount to about 40 inches. 



Epidemics begin in July or August and reach their maximum 

 in October. The charts show plague rising rapidly as soon as 

 the humidity retreats from its maximum. 



