218 [October. 



3 (4) Scape entirely }>lack ; hind tibiae (except beneath) nearly wholly Vilack 



or pitchy, middle tibiae also dark, the hind metatarsi black or very 

 dark ; yellow facial markings continued back along- the eye-margins 

 to about the line of the antennae. 



(Tubercles black, their hind margins bright yelloAv)... 



xanthosticta. 



4 (3) Scape entirely black only in tinusual aberrations ; if so, either the legs 



are not as above or the facial marks are different. 



5 (6) Scape entirely black rujicornis var. 



6 (5) Scape more or less pale in front or beneath. 



7 (8) Spots of the 2nd abdominal segment well separated inwardly (but the 



space between them, where least, is less than one-third the width of 

 the segment), those of the 3rd segment truncate or blunt inwardly 

 and much more widely separated than the preceding (the space 

 between them not less than one-third the width of the segment or 

 often greater than this) ; mesosternum excessively densely clothed 

 with silver hairs, which appear denser and more decumbent than in 

 other forms ; fringe beneath the hind and middle femora dense and 

 unusually short. 



(Yellow orbital lines reaching to about the line of the antennae, 

 the latter appearing longer and more slender than in rujicornis) 



...lateralis. 



8 (7) Spots of the 3rd abdominal segment rarely separatee] as above, and, if 



so, the fringe beneath the middle femora is longer ; mesosternuna 

 less densely clothed, and in some forms the clothing is yellow-tinged, 

 not silver. 



9 (10) All the abdominal bands, from and including that on the 2nd segment, 



wide and entii-e, the apices of the segments mostly dark brown or 

 pitchy; 1st segment with two conspicuous black or very dark rotuad 

 spots in the pale band ; facial yellow markings not nearly extending 

 back to the line of the antennal insertions signata. 



10 (9) If all these abdominal bands are wide and qviite unbroken, then the 



yellow facial markings are continued back (sometimes extremely 

 narrowly) to about the line of the antennae ; i^ale band of 1st 

 segment in many varieties without two conspicuous black spots, but 

 in some they are present. 



11 (12) Wings always conspicuously flavo-hyaline flava. 



12 (11) Wings in nearly all varieties more greyish, without notable yellow 



tint rujicornis. 



So far as the specimens before me are concerned, there is not much 

 difficulty in distinguishing the males of fiava from rvficornis in the 

 case of most varieties of the latter, but this sex of the large form of 

 rujicornis, which parasitizes A. fxdva, is extremely close to flava and 

 separable only with great difficulty. This form also greatly resembles 



