GRAPEVINE FLEA-BEETLES. 



19 



DURATION OF CALLOW PERIOD. 



The duration of the callow period of the adult stage, or the period 

 after transformation of the pupa to adult and before its emergence 

 from the ground, was recorded for 48 individuals. It varied from 

 1 to 4 days, with an average of 2.19 days, as 

 shown in Table XXVI. The period covered 

 by these records extended from July 28 to 

 August 1 1 . 



Table XXIV . — Prepupal 

 stage of A. woodsi, North 

 East, Pa., 1917. 



SUMMARY. 



Number 

 of individ- 

 uals. 



Duration 

 of period. 



29 

 19 



7 

 2 



Days. 

 4 



5 

 6 



7 



157 



M.68 



i Total. 



2 Weighted average. 



The seasonal history of the lesser grape- 

 vine flea-beetle is similar in general to that 

 of the larger species, but it is later through- 

 out. There is a single generation annually, 

 winter being passed in the adult stage. 

 Beetles emerge from hibernation in the latter 

 part of May or early June, some time after 

 the grape shoots have expanded, or about 

 three weeks later than the typical species. Oviposition begins early 

 in June and continues until the latter part of July, when the last 

 adults disappear. 



The average duration of the incubation period was 12.82 days in 

 1916 and 13.72 days in 1917, slightly less than that of the larger 

 species, but this difference may be accounted for by the fact that 

 these incubation records were taken later in the season, when the 

 temperature was higher. 



Table XXV. — Duration of pu- 

 pal stage of A. woodsi, North 

 East, Pa., 1917. 



Table XXVI .— Callow period of 

 adult stage of A . woodsi, North 

 East, Pa., 1917. 



Number 

 of pupae. 



Duration 

 of stage. 



10 

 16 

 17 

 2 



Days. 

 6 



7 

 8 

 9 



145 



2 7.24 



Number 

 of individ- 

 uals. 



Duration 

 of period. 



12 

 19 

 13 

 4 



Days. 

 1 

 2 

 3 



4 



148 



2 2.19 



i Total. 2 Weighted average. i Total. 2 Weighted average. 



Larvai are found on the vines in midsummer, the records of collec- 

 tion extending from June 18 to August 8. The average duration of 

 the larval feeding period was 18.71 days in 1916 and 18.59 days in 

 1917, or about one-fourth shorter than that of the "large form." The 

 duration of the three larval stages was as follows: First stage, 6.16 

 days in 1916 and 6.35 days in 1917; second stage, 6.46 days in 1916 

 and 6 days in 1917; third stage, 6.51 days in 1916 and 6.62 days in 

 1917. 



