32 KEPOKT OF SEARCH FOE ENEMIES OF CITEUS WHITE FLY. 



and averages about 15 inches. Taken as a whole the climate of the 

 Punjab is very comparable 'with that of portions of the arid south- 

 western United States. 



The ^Titer's observations were confined almost entirely to the 

 year 1911, during wliich conditions were somewhat abnormal because 

 of the almost total failure of the rains during the monsoon in the 

 plains of northern India. The prevailing extremely high temperature 

 and low humidity throughout the summer (with the exception of two 

 periods of very light rainfall) gave excellent opportunity for observing 

 the effect of high temperature on the development of the white fly, 

 as well as the effect of humidity on its development and emergence. 

 Throughout the period between April and September the humidity 

 continued so low that at no time was foliage noticeably moistened by 

 dew except in a few instances following precipitation. Heavy dews 

 occur during the autumn and winter months, yet they are much 

 less heavy than in Florida. 



With these considerations regarding Indian weather in mind, an 

 attempt will be made to specify its effect on the development of the 

 white fly during 1911. It is quite probable that the emergence of 

 the first brood at Lahore took place about the 1st of April. By May 

 1 it appeared that practically all eggs had hatched, while the insects 

 were in the earlier stages of development. The temperature during 

 the latter half of April averaged about 82° F. Development con- 

 tinued throughout May, and by June 11 the insects were mostly m 

 the thickened pupal condition or approaching maturity. As com- 

 pared with that of Florida, development thus far had been about 

 normal. The mean temperature from May 1 to June 11 was 93° F. 

 During the period, June 11 to 15, about 2 inches of rain fell, while 

 the humidity, which had averaged about 39 during the preceding six 

 weeks, now rose to an average of 74. This moisture apparently 

 hastened the development of the pupae. A few of the more advanced 

 individuals changed to adults and emerged about 10 days after the 

 rain. Almost immediately folio v/ing this period of precipitation the 

 temperature rose, while the humidity returned to normal. This 

 return to previous hot, dry conditions appeared suddenly to check 

 further development, but such pupse as had already changed to 

 adults began emerging on June 25, 10 days after the last ram. A 

 very light shower of rain fell on June 26 and appeared to bring out all 

 adults ready for emergence. Within four days practically all adult 

 flies had disappeared from the hedge plants. 



This hot, dry weather continued tliroughout July up to August 20. 

 Slight thunderstorms on July 13 and 14 moderated the temperature a 

 few degrees. The very dry, hot atmosphere immediately preceding 

 and following these rains, as well as the sunshine between showers, 

 almost immediately dissipated any marked change of the tempera- 



