HORSE-FLIES AXD WESTERN AGRICULTURE. 



19 



temperature in the sunlight. With the higher mean temperature 

 during the incubation of mass No. 8715, the incubation period was 

 much shorter. The summer of 1919 was unusually hot. It is 

 probable that in nature a few of these egg masses are in direct sun- 

 light very much of the day. Hence the average incubation period 

 in Antelope Valley is probably between 10 and 14 days. When 

 hatching the larvae burst open the shell somewhere near the distal 

 end, and crawl actively out and drop into the water over which 

 they have hatched. 



LARVA. 



No material or data were obtained to indicate the number of 

 molts of T. punctifer. Mitzmain (7) gives three instars for T. 

 striatus Fab., but on account of the vast difference in size between 

 the second instar and the full-grown larva of T. punctifer there can 

 be little doubt that there is an intermediate instar. 



Accurate records were obtained on the pupal periods of 22 speci- 

 mens. These are given in Table 2. 



Table 2. — Pupal periods of Tubanus punctifer. 



No. 



Date of pupa- 



Date of emer- 



Pupal 



Sex. 





tion. 



gence. 



period. 











Days. 





6879-1 



July 7,1919 



July 27,1919 



20 



Female . 1 



6S93-1 



Jul. 8 1919 



July 25,1919 



17 



Do. . 



7648-9 



July 31,1918 



Aug. 28, 1918 



28 



Do. 



10 



Aug. 1,1918 



do... 



27 



Male. 



13 



July 8, 1918 



July 24,1918 



16 



Do. 



129 



July 29,1919 



Aug. 19, 1919 



21 



Female. 



128 



July 28,1919 



Aug. 21, 1919 



24 



Do. 



140 



Aug. 4,1919 



do... 



17 



Do. 



141 



Aug. 5,1919 



Aug. 23, 1919 



18 



Do. 



142 



July 25,1919 



Aug. 10,1919 



16 



Male. 



143 



Aug. 8,1919 



Aug. 25, 1919 



17 



Do. 



145 



Aug. 9,1919 



do... 



16 



Do. 



147 



Aug. 12, 1919 



Sept. 1,1919 



20 



Do. 



148 



....do... 



Aug. 30, 1919 



18 



Female. 



150 



Aug. 13, 1919 



Sept. 1,1919 



19 



Do. 



163 



Aug. 16, 1919 



Sept. 4,1919 



19 



Do. 



164 



Aug. 18, 1919 



Sept. 11,1919 



24 



Male. 



165 



Aug. 16, 1919 



Sept. 5,1919 



20 



Female. 



167 



Aug. 17,1919 



Sept. 3,1919 



17 



Male. 



168 



do... 



Sept. 9,1919 



23 



Female. 



179 



Aug. 21,1919 



Sept. 13, 1919 



23 



Male. 



182 



Aug. 24,1919 



Sept. 22, 1919 



29 



Female. 



The average pupal period was 20.4 days. The average period 

 for males was 19.6 days; for females, 21 days. It will be noted 

 that the period was longer during the latter part of August and 

 September when the temperatures were considerably lower. The 

 temperatures are not given because they would not accurately rep- 

 resent temperatures of the soil in which the larvae pupated. 



Out of a large number of larvae of T. punctifer reared from the 

 egg only four pupated, and only three of these emerged as adults. 

 Table 3 gives the duration of development. 



