The Bionomics of South African Insects. 529 



and might have a similar meaning. Mr. A. J. Chitty 

 also suggested that the same interpretation applies to the 

 Sesiid moth shown on Plate XXII, figs. 15, 16. In this 

 latter case the shape of the opaque area would present 

 during flight a very close approximation to the outline of 

 the narrow fore-wing and small hind-wing of the Diploptera, 

 many of which are figured on the same plate as the Sesiid 

 (compare Figs. 7, 8, 10, 12, etc., with Fig. 16). 



It seems probable that the case of Scolia alaris will 

 throw much light on the manner in which the mimicry 

 of Aculeates is brought about in insects of many orders. 



C. 



Growp with Black Bodies and Yellow Tails, chiefly 

 jDijjloptera (Represented on Plate XXII). 



Hymexoptera. 



Scolkidse. 

 Scolia erythropyga (figs. 

 1,2). 



Pompilidw. 



Salius tamisieri (figs. 3,4). 



,, spectrum (fig. 5). 



Lepidoptera. 



Sexiadx. 

 Trochilium sp. 

 15, 16). 



(figs. 



DiPTERA. 



Bombylius sp. nov. 



(fig. 17). 

 Silvius pertusus (fig. 

 18), 



Eumenidee: 

 Rliyuchiuiu synagro- 



ides (fig. 6). 

 Synagris abyssinica 



(fig. 7). . 

 Synagris mirabilis (fig. 



8). 

 Synagris emarginata 



(figs. 9, 13)._ 

 Synagris analis (figs. 



10, 11). 

 Synagris xanthura (fig. 



12). 

 ^ Eumenes dyschera 



(fig. 14). 



All the Hyraenoptera in this group are common insects 

 occurring in some numbers on suitable flowers. Their 

 metallic blue wings and yellow tails make them very notice- 

 able objects, and tlieir flight is leisurely. Of the Trochilium 

 only two specimens were taken — both of them on the wing, 

 when the resemblance to a large Synagris was most remark- 

 able, being much heightened by the transparent edging of 

 the hind- wing, which is thus made to appear of about the 

 same size and shape as that of the wasp. Of the two 

 Diptera, one, the Bomhylius, is very common, especially 

 about flowers; the other, Silvius pertusus, \s apparently 

 scarce. There is not sufficient evidence to judge on their 

 true relation to the group. 



[The conspicuous yellow apex of the abdomen probably 

 acts as an easily seen directive mark indicating the sting. 

 Compare pages 510 to 512.— E. B. P.] 



TRANS. ENT. SOC. LOND. 1902. — PART III. (NOV.) 35 



