284 THE CANADIAN ENTOMOLOGIST. 



NUMBER OF MOULTS OF THE FEMALE OF DACTYLOPIUS 



CITRIC 



BY ROBERT MATHESON, ITHACA, N. Y. 



The life-history of the male of Dactylopiiis citri has been worked out 

 by Reed in 1890 at Cornell University. His results are embodied in an 

 unpublished thesis. Berlese, '93, in "Le Cocciniglie Italiane Viventi 

 Sugli Agrumi," pp. 23-33, has given a more detailed account of the male's 

 life cycle. It may be well to give here a brief summary of their work 

 before describing the transformations of the female: 



The young nymphs moult for the first time in from 10 to 22 days 



after hatching. During the first stage it is impossible to separate the 



males from the females by their external characters, and only just previous 



to this moult can they be distinguished. Berlese has shown that the 

 future mouth-parts of the female which is about to shed its skin, are coiled 

 spirally just beneath the transparent cuticle. In the males no developing 

 mouth-parts can be observed, and those which they possess disappear at 

 the time of the first moult. These facts can be observed just before the 

 moult. 



The cast skins usually remain attached to the caudal extremity of the 

 male nymphs. In the second stage the male nymphs are sluggish in their 

 movements. They usually seek out some secluded spot and, in about ten 

 days, begin spinning their cocoons. The spinning of the cocoon occupies 

 about two days, and, shortly after its completion, the second moult occurs. 

 This cast skin is, in a day or two, pushed out at the caudal end of the 

 cocoon. It is during the second stage that the beginning of the wings 

 and halteres may be noted. They appear as small papillce on the 

 mesothoracic and metathoracic segments. 



The third moult occurs five days after the second, and a week later 

 they moult for the last time. The perfect winged insects emerge from the 

 cocoon in from three to four days after the fourth moult. 



The life-history of the female is in marked contrast to that of the male. 

 Neither Reed nor Berlese, nor any previous worker, succeeded in 

 determining the number of moults in the female. Reed supposed there 

 were three, whereas Berlese, reasoning from analogy with the male, 



considered there must be at least four. 



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*Contribiition from the Entomological Laboratory of the Cornell University. 



Augfust, 1907 



