THE GRAPE CURCULIO. 11 



being 261.66. 1 The first eggs were deposited on July 3 and the last 

 on September 5, oviposition by all the beetles covering a period of 

 65 days. The greatest number of eggs laid by a female in a single 

 day was 16, and this record was made in only one instance. Another 

 beetle laid 15 eggs in a day and there were six cases in which 14 eggs 

 were laid in a day. The period of greatest egg production was from 

 July 13 to August 12, 81.9 per cent of the eggs being deposited between 

 these dates. The maximum number of eggs for one day was 244; 

 these were produced on July 3 1 . 



ACTIVITY OF THE BEETLES AT NIGHT. 



During the progress of the investigation it became apparent that 

 the beetles were ovipositing and feeding on the leaves to some extent 

 during the night, and, to obtain data on this point, 5 pairs of beetles 

 were confined in cages in the insectary on July 19 and kept under 

 observation until August 3, a period of 14 days. The beetles were 

 provided with fresh grapes and leaves three times daily, at 5 a. m., 2 

 12 m., and 7 p. m., the duration of the forenoon period being 7 hours, 

 that of the afternoon period 7 hours, and that of the night period 

 10 hours. Each time the grapes and leaves were changed in the 

 cages counts were made of the eggs and leaf-feeding marks pro- 

 duced during the period just ended. The counts showed a total of 

 455 eggs produced by the 5 females for the entire period. Of this 

 number 85 were deposited during the forenoon period, 148 during 

 the afternoon period, and 222 during the night period. The average 

 was 16.6 eggs for each of the 14 hours of daylight and 22.2 eggs for 

 each of the 10 hours of darkness. Feeding on the leaves was more 

 active by day than by night. The 10 beetles during the daylight 

 periods made 1,072 feeding marks, or an average of 78 for each of 

 the 14 hours of daylight, and 376 during the night period, or an 

 average of 37.6 for each of the 10 hours of darkness. 



TIME REQUIRED FOR EGGS TO HATCH. 



About 50 eggs deposited on July 17 hatched on July 23 and an 

 equal number deposited on July 21 hatched on July 27, the period 

 of incubation in both cases being 6 days. Differences in temperature 

 probably would produce a variation of a day or two in the length of 

 this period. 



All the eggs of a female that had been separated from males for 33 

 days were found to be fertile, although in nature copulation continues 

 at frequent intervals until the end of the egg-laying season. 



1 It is interesting to note that the average number of eggs laid by 30 females from which a record was 

 obtained in 1905 (30) was 257.46, a difference per individual for the two lots of beetles of only 4.2 eggs. 



2 All references to clock time refer to "Standard time. " 



