56 BULLETIN 536, U. S. DEPARTMENT OF AGRICULTURE. 



under identical conditions 6 larvae required 9.5 days in a ripe but still 

 hard peach. 



All data secured by the writers indicate that during the warmest 

 portions of the year larval development progresses rapidly and fairly 

 uniformly. With the approach of colder weather larval life is not 

 only lengthened but subject to considerable and entirely unexplainable 

 variation, even with larvae hatching at the same time in the same 

 fruit, especially if the host fruit happens not to be in the best condi- 

 tion to support larval life. The three larvae requiring 19, 25, and 35 

 days for development in a very hard apple furnish a good example. 

 In Table XV are recorded data showing the ability of cold weather 

 greatly to increase larval life. 



The data in Table XIV indicate that under favorable conditions as 

 regards temperature and host the first larval instar is passed in from 

 26 to 48 hours, the second in 24 to 48 hours, and the third in 48 to 265 

 hours. It is profitable, therefore, to compare these and other data in 

 Table XIV with the data of Table XV. 



At an elevation of 8,250 feet, on the summit of Mauna Hualalai, 

 Hawaii, where the temperature ranged between 27° and 73° F., 

 but averaged for the period about 48° F., the first larval instar was 

 found to range up to 57 days. Eighty-nine larvae in apples were 

 found still in the first instar after 30 days, 3 after 46 days, 7 after 54 days, 

 and 1 after exposure for 57 days. Thirty-three larvae in the second instar 

 placed on Hualalai were still in this instar after 32 days, and 1 after 54 

 days. At Strawberry, Hawaii, a ranch station, where the temperature 

 ranged from 39° to 79° F., 49 first-instar larvae were found still in 

 this instar after 27 days and 19 after 29 days. At Kealakekua, 

 where the temperature ranged between 58° and 80° F., with a mean 

 of about 68° F., three larvae in apples required 28, 58, and 74 days to 

 become fully grown and to leave the fruit to pupate. 



In cold storage under what may be called artificial conditions, 

 larval life may be variously prolonged. Thus one second-instar larva 

 and one third-instar larva in peaches placed in storage at temperatures 

 varying from 40° to 45° F. were found still in those instars at the 

 end of 29 and 45 days, respectively, while check larvae at the labora- 

 tory in the same species of host fruit completed their entire develop- 

 ment in from 6 to 9 days. Three third-instar larvae in apples placed 

 in a refrigerator at temperatures varying from 48° to 52° F. were 

 still active after 60 days and one was alive after 79 days. In a 

 second refrigerator at temperatures ranging from 58° to 62° F., 

 larvae completed their development and pupated in 24, 36, 40, 44, 

 and 50 days. 



