LIFE HISTOEY. 



Record sJioiving fecundity of San Jose scale. 



49 



Number of tree. 



Males. 



Females. 



Total. 



Number of tree. 



Males. 



Females. 



Total. 



1 



Progen 



72 

 77 

 138 

 18 

 98 

 33 

 13 



/ of overu 

 females. 

 34 

 43 

 60 

 22 

 60 

 25 



intered 



106 



120 



198 



40 



158 



58 



13 



gcner- 



585 

 502 

 417 

 312 

 556 

 330 



1 



Progeny of third 

 Hon. 

 110 307 

 122 464 

 190 284 

 187 400 

 174 280 

 107 274 



genera- 

 417 



2 



3 



4 



2 



3 .. 



4 



5 



6 



586 

 474 



587 



5 



454 



6 . 



354 



7 



1 



Progenii of fourth 



genera- 

 561 





Progeny of seconc 

 nh'nn. 



242 

 112 

 92 

 210 

 242 

 156 



tion. 

 319 

 230 

 170 

 344 

 343 

 293 



1 



350 

 276 

 325 

 192 

 415 

 206 



235 

 226 

 92 

 120, 

 151 

 124 



2 



342 



2 



3 



4 



5 



262 



3 



554 



4 



585 



5 



6 



449 











Perhaps the most notable feature of the foregoing records is the 

 result obtained from the overwintered females. It will be seen that 

 the males greatly predominate in this generation, and that the numbers 

 of both sexes are insignificant compared with the progen}^ of the later 

 generations. The males still predominate in the second generation, 

 but in the third and fourth generations the females considerably out- 

 number the males, in one instance the females from a single mother 

 reaching the astonishing number of 464, which, with 122 males from 

 the same parent, makes the progen}^ of this female 586 insects. Tak- 

 ing 200 females as an average of the different generations for the 

 3^ear, the product of a single individual from spring to fall amounts to 

 1,608,040,200 females. In one instance we have over 415 males from 

 a single female, and while the number of males would average some- 

 what less than the females, taking the summer thru, yet, having 

 underestimated the females, the males may be estimated at the same 

 number, giving a total of 3,216,080,400 descendants from a single 

 insect in a single season. It is not to be expected, of course, that all 

 the individuals from a scale survive and perform their function in life, 

 but under favorable conditions, or in the case of a tree newly infested 

 or not heavily incrusted, the vast majority undoubtedly go thru their 

 existence without accident. Neither the rapidity with which trees 

 become infested nor the fatal effect which so early follows the appear- 

 ance of this scale insect is therefore to be wondered at. 



Owing to the long period during which the female is continuously 

 producing 3^oung the different generations or broods in the course of the 

 summer are not distinctl}^ marked and merge insensibly into each other — 

 so much so that at almost an}" time there will be found young larva? 

 f'unning about over the trees and scales in all stages of development. 

 Still, at certain times the young will be noticeabl}^ more abundant, 

 indicating periods when the majority of each generation are producing 

 young. In this latitude the first young appear, as noted, by the middle 



