THE CANKERWORMS, 



25 



Table 10. — Incubation of eggs of the spring cankerworm, Wallingford, Conn., 

 1920 and 1921— Continued. 



IN 1921— Continued 



Eggs laid— 



Eggs 

 hatched- 



Mar. 28. 



Do. 



Do. 

 Mar. 31 



Do. 

 Apr. 1.. 



Do. 



Do. 

 Apr. 2.. 



Do. 



Do. 



Do. 



Do. 



Apr. 29 

 Apr. 30 

 May 1 

 Apr. 29 

 May 1 

 Apr. 28 

 Apr. 29 

 Apr. 30 

 Apr. 29 

 Apr. 30 

 May 1 

 May 2 

 May 3 



Number 

 of eggs. 



Incu- 

 bation 

 period. 



Days. 

 32 

 33 

 34 

 29 

 31 

 27 

 28 

 29 

 27 

 28 

 29 

 30 

 31 



Eggs laid- 



Eggs 

 hatched- 



Apr.3.. 

 Do. 

 Do. 

 Do. 



Apr. 4.. 



Do. 

 Apr. 5.. 



Do. 



Apr. 29 

 Apr. 30 

 May 1 

 May 2 



...do 



May 3 

 May 6 

 May 8 



Number 

 of eggs. 



Maximum period 



Minimum period 



Average period 



Total individuals, 550. 



Incu- 

 bation 

 period. 



26 

 27 

 28 

 29 

 28 

 29 

 31 

 33 



44 

 26 

 32.7 



TIME OF HATCHING OF THE EGGS. 



The eggs of the spring cankerworm hatch at approximately the 

 same time as those of the fall species. Just before hatching, the eggs 

 turn dark, almost black. Table 11 gives hatching records for 38 

 egg masses collected in the field early in April, 1920, and for 19 egg 

 masses laid in the insectary in 1921. The spring of 1920 was unus- 

 ually late, while that of 1921 was equally early, giving a difference 

 of about four weeks in the two seasons. 



Table 11. — Hatching of eggs of the spring cankerworm, Wallingford, Conn., 



1920 and 1921. 



FROM 38 EGG MASSES COLLECTED IN THE FIELD IN 1920. 





Number 



of eggs 



hatched. 



Temperature. 



Date. 



Number 



of eggs 



hatched. 



Temperature. 



Date. 



Maxi- 

 mum. 



Mini- 

 mum. 



Aver- 

 age. 



Maxi- 

 mum. 



Mini- 

 mum. 



Aver- 

 age. 



May 14 



May 15 



May 16 



May 17 



May 18 



May 19 



- 30 



* 58 

 205 

 217 

 78 

 59 



o p 



54 

 64 

 71 

 74 

 71 

 75 



o p 



45 

 46 

 43 

 47 

 46 

 45 



o F 



48.7 

 54.8 

 58.1 

 60.6 

 58.0 

 58.8 



May 20 



May 21 



May22 



May23 



May24 



70 



3 



21 



10 



4 



o F 

 76 

 59 

 66 



58 

 66 



o p 



51 

 53 



48 

 46 

 47 



o p 



61.1 

 56.0 

 55.2 

 51.3 

 53.2 



FROM 19 EGG MASSES LAID IN THE INSECTARY IN 1921. 



Apr. 20 

 Apr. 21 

 Apr. 22 

 Apr. 23 

 Apr. 24 

 Apr. 25 

 Apr. 26 

 Apr. 27 

 Apr. 28 

 Apr. 29 



2 



73 



36 



54.0 



47 



76 



49 



60.5 



10 



78 



49 



60.9 



8 



64 



45 



52.2 



82 



67 



42 



54.3 



134 



76 



47 



59.2 



24 



73 



44 



57.6 



20 



68 



51 



58.4 



133 



73 



56 



64.0 



111 



72 



51 



59.8 



Apr 

 Mas 



30. 

 1.. 



May 2.. 

 May 3 . . 

 May 4.. 

 May 5.. 

 May6.. 

 May 7 . . 

 May 8.. 



53.8 

 47.5 

 52.4 

 55.8 

 54.8 

 45.1 

 47.0 

 51.0 

 56.9 



