13 



SOME ACULEATE HYMENOPTERA OF HALIFAX. 



O.C. SILVERLOCK. 



The species mentioned below were all taken during the 

 summer of 1908. 



Heterogyna : — 



Formica jusca (typical) abundant everywhere. One nest, 

 under a large stone, had no less than eighteen apterous females. 



F. fiisca {rufiharbis) abundant in the Hebden Bridge 

 district. 



F. nifa occurs at Hebden Bridge and Hardcastle Crags. 



These three closely allied forms are peculiarly interesting. 

 The ordinary observer would detect no difference between the 

 workers of F. rufa and F. jusca (var. nifibarhis), but at the same 

 time, he would not for a moment imagine that there was any 

 close similarity of structure between the two races of the latter. 

 The only difference noticeable with a lens between F. riifa and 

 F. jusca {nifibarhis) lies in the comparative dullness or bright- 

 ness of the frontal area. 



Structurally, the races of F. jusca are almost indistinguish- 

 able, yet their colour varies from a dark bronzy black to the 

 reddish tint of F. ruja. In between these extremes there 

 is almost every possible shade of colour. 



In habits the typical jusca almost. in\'ariably chooses tO' 

 form its nest under large flat stones. Its race, however, prefers 

 to tunnel underground, and nija always forms the well-known 

 mounds of pine-needles, etc. 



Lasius niger — the common garden ant of southern counties — 

 I only found once in North Dean Woods ; L. flaviis, almost 

 equally common in meadows in the south, I never found at 

 all. 



Myrmica rubra — two races only were found ; laevinodis 

 and VMginodis, these were both commonly seen, yet scabrinodis, 

 the commonest race of the south, I never found. Several nests 

 of laevinodis were infested with parasitic acari, which had 

 attached themselves to the bodies of the ants, often in most 

 ' peculiar positions. 



Leptothorax acervorum — a single specimen from Hebden 

 Bridge. 



FossoRES : — 



Fam. Pompilidae — the only insect of this most fascinating 



igio Jan. i. 



