CONCLUDING REMARKS. 107 



sition to the Bees, the females after copulation will probably de- 

 posit those fertilized eggs from which only males are developed. 



Hence it may happen that here and there in the open air we 

 find the male and female individuals living together by them- 

 selves, and separate from each other. With this, the observa- 

 tion of Zinke stands in perfect accordance*, that many Sac- 

 bearers only occur in separate sexes during their larva and pupa 

 state, and that where one sex is met with, the other may be 

 sought for in vain. A communication made to me by letter by 

 Heyden may also find an explanation by this : Heyden observed 

 in the genus Coccus that the males live in company separated 

 from the females, until they are perfectly developed. 



The male individuals in the larva state probably lead quite a 

 different mode of life in Psyche Helix, and might in consequence 

 have hitherto escaped the observation of those entomologists 

 who hoped to find the caterpillars of the males of Psyche Helix 

 as Sac-bearers with a convoluted dwelling. For these assertions 

 of mine, which are only expressed as suppositions, a support 

 may be found in an observation which was made by Leon 

 Dufour. From a particular gall, he always reared nothing but 

 female individuals of the Hymenopterous insect Stomoctea, but 

 was much astonished when he obtained nothing but males of 

 this insect from the pupa of a Tenthredo^. 



* See, Germar's Magazin der Entomologie, i. 1813, p. 31. 



\- See Leon Dufour, Recherches, fyc., p. 528. To the observation that he 

 had only been able to obtain females of Diplolepis gallce tinctorice, he adds the 

 following interesting remark: "J'engage les entomologistes a nous faire 

 connaitre le male de cette espece, la plus grande de nos contrees. II serait 

 bien curieux de constater si les oeufs qui ne produisent que des males sont 

 tons pondus dans une espece de galle, et ceux des femelles dans une autre. 

 Je puis citer a 1'appui de cette question un fait digne de remarque. En juin 

 1833 j'obtins, des galles de la Scrophulaire canine, produites par YEulophus 

 Verbasci, un petit Hymenoptere du groupe des Cynipsaires, appartenant a un 

 genre nouveau, que ses mandibules pectinees m'ont fait appeler provisoire- 

 ment Stomoctea. II en naquit au moins une cinquantaine d'individus, mais 

 tous, sans exception, femelles. En juin 1834, je ne fus peu surpris de voir 

 eclore d'une chrysalide de Tenthredo^l&cee dans un verre clos, une quarantaine 

 d'individus de la meme espece de Stomoctea, tous du sexe masculin. Que 

 n'avons-nous pas a apprendre encore sur les Hymenopteres gallicoles et 

 pupivores, soit quant a la determination des especes, soit quant a leur genre 

 de vie et aux merveilles de leur organisation viscerale ! " 



