16 



BULLETIN 438, U. S. DEPARTMENT OF AGEICULTURE. 



Thus 88.7 per cent of all the cocoons were formed less than 1 inch 

 below the surface of the soil. This approximates the percentages 

 found at this depth in California. 



Tables XI, XII, and XIII indicate the period spent in the cocoon 

 in California : 



Table XI. — Cocoon records of the pear leaf-worm, 1911-12. 



Place. 



Date of spin- 

 ning cocoon. 



Date of adult 

 emergence. 



San Jose, Gal 



May 13,1911 

 May 16,1911 

 do 



Mar. 25,1912 

 Mar. 18,1912 



Do. 

 Mar. 4, 1912 

 Mar. 10,1912 



Do. 



Do 



Do 



Red Bluff, Cal 



Do 



Apr. 25,1911 

 Apr. 26,1911 

 do 



Do 







Table XII. — Cocoon records of the pear leaf-worm, 1912-lS. 



Place. 



Date of spin- 

 ning cocoon. 



Date of adult 

 emergence. 



San Jose, Cal 



May 9, 1912 

 May 10,1912 

 May 11,1912 

 do 



May 12,1912 

 May 15,1912 



Mar. 23,1913 

 Mar. 30,1913 

 Mar. 28,1913 

 Mar. 8, 1913 

 Mar. 31,1913 

 Mar. 7, 1913 





Table XIII. — Cocoon records of the pear leaf-worm, Walnut Creelc, Cal., 191S-14. 



Date of 



spinning 



cocoon, 



1913. 



Date of 

 adult 

 emer- 

 gence, 

 1914. 



Date of 



spinning 



cocoon, 



1913. 



Date of 

 adult 

 emer- 

 gence, 

 1914. 



Date of 



spinning 



cocoon, 



1913. 



Date of 

 adult 

 emer- 

 gence, 

 1914. 



Date of 



spinning 



cocoon, 



1913. 



Date of 

 adult 

 emer- 

 gence, 

 1914. 



May 2 

 May 3 



Do 



Do 



Do 



Do. 



Mar. 18 

 Mar. 14 

 Mar. 15 

 Mar. 18 

 Mar. 19 

 .do 



May 4 



...do 



...do 



May 5 

 ...do 



May 6 

 ...do 



May 7 



Mar. 18 



...do 



Mar. 19 

 Mar. 15 

 Mar. 20 

 Mar. 18 

 Mar. 20 

 Mar. 18 



May 7 

 May 8 



...do 



...do 



...do...;. 

 May 9 



...do 



...do 



Mar. 20 

 Mar. 19 

 Mar. 20 

 Mar. 21 

 Mar. 29 

 Mar. 16 

 Mar. 18 

 Mar. 19 



May 9 

 ...do 



May 12 

 ...do 



May 13 

 ...do 



May 14 



May 16 



Mar. 20 

 Do. 

 Do. 



Mar. 25 

 Mar, 18 

 Mar. 19 

 Mar. 31 

 Mar. 22 



Do 



May 4 

 Do 



Mar. 20 

 Mar. 15 

 Mar. 18 



The average time spent underground in a cocoon, first as larva and 

 secondly as pupa, is about 10 months and 10 days. Table XIV 

 summarizes the adult emergence recorded in Table XIII. 



Table XIV. — Summary of Table XIII, adult emergence of the pear leaf-worm, 1914. 



Number 





Number 





of adults 



Date. 



of adults 



Date. 



issuing. 





issuing. 





1 



Mar. 14 





Mar. 21 



3 



Mar. 15 





Mar. 22 



1 



Mar. 16 





Mar. 25 



8 



Mar. 18 





Mar. 29 



8 



Mar. 19 





Mar. 31 



8 



Mar. 20 







