24 Bulletin of the Brooklyn Entomological Society Vol. XV 



THE GROWTH OF INSECT EGGS AFTER OVIPOSITION. 



By J. R. DE.LA ToRRE-BuENO, White Plains, N. Y. 



Mr. Charles Macnamara, in his recent article " Remarks on 

 CoLLEMBOLA,"^ Comments on the oviposition of these primitive 

 insects, remarking on the comparatively large size of the eggs 

 as compared with the mother. Then he goes on to say "we 

 shall not know whether . . . more than one female contributes 

 to the egg cluster, or whether we must accept the decidedly im- 

 probable suggestion that the eggs increase in size after laying."^ 

 (Italics inserted.) 



The fact is that the growth of insects' eggs after depositing 

 is not an entirely unknown phenomenon. The post-ovarian 

 growth of the eggs of certain ants (Packard) and parasitic 

 Hymenoptera (Henneguy) is too well known to merit more 

 than an allusion. In Canadian Entomologist^ is the statement 

 that the ova of Belostoma flumineum grow after depositing while 

 maturing, and also change in form. 



A priori there would seem to be no reason why growth, one 

 element in the development of the insect egg, should not continue 

 outside the ovary. If the chorion be soft and elastic, growth 

 would not be inhibited, and in the primitive insects, such as the 

 Collembola, phenomena such as this might be expected, just as 

 extra-uterine embryological development occurs in the marsupials 

 among mammals, and in the extremely primitive Echidna ; and 

 just as snake's eggs grow after depositing. 



In fact, Collembola on emerging are perfect though small 

 replicas of the parent ; but in the more highly developed and 

 specialized insects, we find a greater degree of extra-ovarian de- 

 velopment and consequently greater immaturity of the ovum and 

 of the larval form, which differs most markedly from the adult. 

 On the other hand we have forms in which nearly the whole 

 embryonic cycle take place within the body of the mother, or 

 wholly so as in the parthenogenetic aphids. 



We can draw no hard and fast Jine between the most imma- 

 ture oviparity and the most advanced viviparity in insects, of 

 which the growth of the egg after depositing is only one to be 

 expected phase. 

 1 Can. Ent., LI : 73-80, 1919. 2 Qp. cit., p. 79. s XXXVIII : 193. 



