70 



BULLETIN 1235, U. S. DEPARTMENT OF AGRICULTURE. 



Table 59. — Oviposition by individual codling moths of the first brood, Yakima, 

 Wash., 1919 — Continued. 



SUMMARY. 



Average. 



Maxi- 

 mum. 



5.00 



19 



12.52 



21 



8.52 



16 



4.72 



11 



4.04 



14 



15.24 



27 



29.94 



173 



8.37 



78 



Mini- 

 mum. 



Number of days before oviposition 



Number of days from emergence to last oviposition 



Number of days of oviposition 



N umber of days on which oviposition occurred , 



Number of days female moth lived after last oviposition . . 



Totallength of life of female moth in days 



Number of eggs deposited by one female moth 



Number of eggs deposited by one female moth in one day 



HATCHING OF THE EGG. 



When the larva is ready to leave the egg it moves its head back 

 and forth as if to stretch the eggshell. The mandibles are moved 

 about rapidly until the point of one of them is forced through the 

 chorion, always at some place on the periphery of the egg. An 

 opening the size of the head is soon made m the eggshell and the 

 larva crawls quickly out. Occasionally, a larva has been observed 

 to kill itself in an effort to emerge from the egg by projecting 

 the anal end first through a hole smaller than its head. 



DATE OF HATCHING OF LARVAE. 



Since the time when the first, the last, and the maximum number 

 of larvae of each brood of the codling moth hatch and enter the 

 fruit is the most important phase of the life-history studies in their 

 practical application to control measures, a comparative diagram of 

 the hatching during 1919, 1920, and 1921 is given in Figure 35. 

 It will be noticed that the hatching curves for the first brood are 

 entirely unlike, and that the first larvae in 1919 hatched 5 days 

 later than the first larvae in 1921, and the first in 1920, 6 days later 

 than the first in 1919. The maximum hatching in 1921 occurred only 

 7 days after the first hatching, and this was 10 days earlier than the 

 date of maximum hatching in 1919, and 20 days before that of 1920. 



The hatching curves of the second brood are much more alike 

 than those of the first brood, and the dates of the first and maxi- 

 mum hatching are nearly the same. It will be noticed that the 

 dates of the first hatching in 1919 and 1921 are identical, and that 

 for 1920 is 11 days later. The date of maximum hatching in 1920 

 is also identical with that in 1921, in spite of the difference of 11 

 days in the date of hatching of the first larvae, and the date of maxi- 

 mum hatching of second-brood larvae in 1919 is but 5 days earlier. 

 Figure 35 shows the necessity of accurate life-history data wherever 

 efficient and economical control is to be obtained. 



HABITS OF NEWLY-HATCHED LARVAE. 



Directly upon emerging from the egg the young larvae seek food, 

 which in the case of the codling moth is preferably the fruit of the 

 apple or pear. Occasionally they will burrow into the veins and 

 stems of leaves, and even into the terminal twigs (as shown in PL 

 III, fig. 1). However, of about 250 newly-hatched larvae which 



