GRAPEVINE ROOT WORM 



21 



An examination of the above record shows that one female 

 taken July 2 began laying eggs July 4 and from then to the 13th 

 deposited from 20 to 30 daily, and from the latter day onward 

 the eggs were laid usually at intervals of one to several days, 

 the periods of deposition being interspersed by intervals of feed- 

 ing. There seems to be a very direct connection between the 

 amount eaten and the number of eggs laid, which would be ex- 

 pected when it is remembered that a single female lived upward 

 of two months and during that time deposited the enormous 

 number of 902 eggs. This record is a striking testimony to the 

 care bestowed on the insects by Mr Walker, who had charge of 

 the breeding cage work. Analysis shows that 257, or over one 

 fourth of the total number, were laid during the first 10 days, 

 and 416, or nearly one half of the total number, in the first three 

 weeks. This record is undoubtedly exceptional and probably 

 approaches the maximum capacity of the insect, particularly in 

 the field. It will be seen, however, that one other female de- 

 posited 342 and another 156 eggs, while averages of beetles kept 

 in certain stock jars ranged from 141 to 192 and 488 to each 

 female, and an average based on the entire record gives nearly 175 

 for each female. This indicates that our highest record, 902, may 

 not be so very exceptional. A study of the entire number of 

 eggs is not without interest, as it shows when the greatest num- 

 ber are deposited and consequently the time when the beetles 

 should be destroyed in order to obtain the maximum benefit. 

 A summarized table is given below. 



Summary of oviposition record 1903 



DATE 



Pair 1 



Pair 5 



Pair 19 



Stock 

 jarl 



stock 

 jar 3 



Check 

 plant 



Total 



Per cent 

 of total 



July 4-18 

 July 19-31 

 July 4-31 



321 

 179 

 500 



165 



25 



190 



55 

 "55' 



2 987 

 1 403 

 4 390 



1 110 



810 



1 920 



435 



758 

 1 193 



5 073 

 3 175 



8 248 



45 

 t28 

 t73 



Totals, July- 

 Sep 



902 

 902 



342 



342 



156 

 156 



5 664 

 141 



2 199 

 192 



1 955 



488 



11 173 





Average per fe- 

 male 











It will be seen from an examination of this that 5073 eggs were 

 deposited by all of the different beetles in the various jars be- 

 tween July 4 and 18 (or the first two weeks) making a total of 



