1892. J 3 



suggested themselves. This must necessarily be different in those 

 genera which infest Andrena, and those which attack Halictiis, seeing 

 that whereas the $ Halictus hibernates, the AnclrencB live for com- 

 paratively but a short time. Moreover, the (^ Halicti all perish at 

 the approach of winter. What, then, becomes of the $ parasite which 

 is embedded in the body of these ($ Halicti ? 



I see no escape from the conclusion that all these perish also, and 

 that only those females which are contained in the ? Halicti survive. 



This seems certain, as the larval parasites do not develop till after 

 the hibernation of the bee. In the autumn, when the Halicti emerge, 

 the body of the female parasite contains only multitudes of developing 

 embryos, and it is only in the spring and early summer, after the 

 hibernation of the bee, that the larvae of the parasite escape into its 

 dorsal canal fully developed. Before this time the ^ Halicti have all 

 long since perished. 



The most puzzling part of the matter is that in some cases only 

 the ^ Halicti seem to be attacked by the parasite, the ? not at all, or, 

 at least, very rarely. In 1886 and 1887, 1 took hundreds of ^ Halictus 

 tumulorum stylopized, but no $ , nor have I ever seen that sex attacked. 

 In these cases, perhaps, the parasites (unlike the others above men- 

 tioned) do develop in the autumn, and are set free as larvce before the 

 death of the Halictus, and then hibernate in their first stage. 



It is certain that many of these parasites, especially those which 

 infest Halictus, must be parthenogenetic. For instance, amongst all 

 the H. tumulorum examined there was no sign of a c^ parasite 

 having escaped from any one of them. 



The species of Andrena and Halictus which I have myself found 

 or seen recorded by others as being liable to be attacked are : — 



Halictus ruhicundus, Chr. ; S. xanthopus, Kir. ; H. 4-notaftis, Kir. ; S. al- 

 bipes, Kir. ; H. cylindricus, Fab. ; H. nitiditcsculus, Kir. ; H. minutissimus, Kir. ; 

 H. tumulorum, Linn. ; H. morio, Fab. 



Andrena atriceps, Kir.; A. Trimmerana, Kir.; A.fulva,^c\\.; A. nigrocenea, 

 Kir. ; A. Gioynana, Kir. ; A. proecox, Scop. ; A. varians, Rossi ; A. lahialis, Kir. ; 

 A. minutula, Kir. ; A. nana, Kir. ; A. Afzeliella, Kir. ; A. WllJcella, Kir. 



No doubt other species could be added to this list by other Ento- 

 mologists, as several of the species herein recorded, so far as I know, 

 have not previously been noticed as stylopized. 



Stylopized bees are exceedingly local, though often plentiful where 

 they are found at all ; many colonies of some of our commonest 

 Andrenidce may bo examined in many localities without a single 



X -2 



