APPENDIX. 369 



Perhai^s the most notable feature of the foregoing record 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 progeny of the later generations. The 

 males still predominate in the second generation, but in the third and fourth 

 generations the females considerably outnumber the males, in one instance 

 the females from a single mother reaching the astonishing number of four 

 hundred and sixty-four, which, with one hundred and twenty-two males 

 from the same parent, makes the progeny of this female five hundred and 

 eighty-six insects. Taking two hundred females as an average of the dif- 

 ferent generations for the year, the product of a single individual from 

 spring to fall amounts to one billion six hundred and eight million forty 

 thousand two hundred females. In one instance we have over four hundred 

 and fifteen males from a single female, and while the number of males would 

 average somewhat less than the females, taking the summer through, yet, 

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

 number, giving a total of thi'ee billion two hundi-ed and sixteen million 

 eighty thousand four hundred 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 condi- 

 tions, or in the case of a tree newly infested or not heavily incrusted. the 

 vast majority undoubtedly go through their existence without accident. 

 Neither the rapidity with which trees become infested nor the fatal effect 

 which so early follows the appearance of this scale insect is therefore to be 

 wondered at. 



Owing to the long" period during which the female is continuously pro- 

 ducing young, the different generations or broods in the course of the sum- 

 mer are not distinctly marked and merge insensibly into each other — so 

 much so that at almost any time there will be found j'oung larvae running 

 about over the trees and scales in all stages of development. Still at certain 

 times the young will be noticeably 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 of May, at Armherst, M assachusetts, 

 they were first noticed June 12, and in Arizona they are recorded as appear- 

 ing in March. The larvae are continuously present on the trees until fur- 

 ther hatching is prevented by severe frosts. In 1894, as we have already 

 shown on page 289 of Volume VII of Insect Life, the first frosts at Wash- 

 ington occuri'ed in the latter part of October and the hatching of the young 

 ceased before the first of November. October 24, 1894, however, Mr. Howard 

 saw recently settled larva?, not more than five days old, at LeAvis1)urg. 

 Pennsylvania. In 1895, the October frosts were insignificant, and in this 

 neighborhood no severe frosts occurred until about the first of December. 

 The result was that young larvae were found at Washington until late in 

 November, while on twigs received fromChestertow'n, Maryland. November 

 13 and November 27. the young were more or less abundant. The cold spell 

 of the last week in November and the first week in December put a stop to 

 development here. This same cold spell was of very wide extent. As far 

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