GKAPEVINE FLEA-BEETLES. 



9 



The period covered by records of larvae in the soil extended from 

 June 19, when the first larvae entered the ground, to July 27, when 

 the latest adults emerged. The variation in duration of this period 

 is shown in Table II. 



EMERGENCE FROM HIBERNATION AND OVIPOSITION IN 1917. 



The earliest record of adult emergence is May 11, at which time 



grape buds were swelling. Eggs were first found May 18. Adult 



beetles were found on grapevines until 



■ t i , , , o T -i xl _■• Table II. — Period in around of 



the latter part of June, when they disap- A chalybea, North East, Pa., 



peared altogether. 1916. 



INCUBATION PERIOD IN 1917. 



The duration of the incubation period 

 in 1917 (see Table III) varied from 13 to 

 21 days, with an average of 15.18 days, 

 as shown in Table III. The period cov- 

 ered by records on the incubation period 

 extended from May 26 to June 28. 



LARVAL FEEDING PERIOD. 



The duration of the larval feeding period 

 of 46 individuals of Altica chalybea reared 

 to adults varied from 19 to 33 days with an average of 24.26 days. 

 The period covered by records of feeding larvae extended from June 

 4, the earliest date of hatching, to July 20, the latest date, when 

 larvae entered the ground. Complete data on the larval feeding 

 period are given in Table IV. 



Number of 



Duration 



individuals. 



of period. 





Days. 



2 



15 



1 



16 



4 



17 



7 



18 



10 



19 



16 



20 



8 



21 



20 



22 



12 



23 



7 



24 



187 



3 20.71 



i Total. 



1 Weighted average. 



Table III — 



Incubation period of 



A. chalybea, North East, Pa., 1917. 



Date of 



Date of 



Number 



Duration 



Date of 



Date of 



Number 



Duration 



oviposition. 



hatching. 



of eggs. 



of period. 



oviposition. 



hatching. 



of eggs. 



of period. 









Days. 









Days. 



May 26 



June 14 



6 



19 



June 2 



June 15 



10 



13 



26 



16 



6 



21 



2 



16 



4 



14 



29 



12 



1 



14 



2 



17 



5 



15 



31 



13 



4 



13 



2 



IS 



2 



16 



31 



14 



4 



14 



2 



19 



2 



17 



31 



15 



2 



15 



4 



19 



25 



15 



31 



16 



2 



16 



4 



20 



17 



16 



June 1 



14 



12 



13 



13 



28 



1 



15 





15 

 16 





14 

 15 











1 



1 







1108 



2 15. 18 



1 Total. 2 Weighted average. 



DURATION OF FIRST LARVAL STAGE. 



The duration of the first stage, of 68 larvae reared, varied from 

 4 to 14 days with an average of 8.74 days, as is shown in Table V. 

 The total period covered by records on larvae in this stage extended 

 from June 4 to July 2. 



1833°— 20 2 



