1. THEREVA 



545 



Fig, 



318. — Thcreva nohili- 

 tata ?. X 30. 



slightly produced towards the antennse, bearing in the male long dense pubescence, 

 but in the female only short pubescence ; a transverse shining black bare callus 

 (sometimes divided into two spots) is almost always present on the broad frons of 

 the female, and though this callus varies in shape it does not give infallible specific 

 distinction. Face sloping or gently curving down to the mouth, and bearing in the 

 male long dense pubescence, Avhich extends round under the eyes and all up the 

 back of the head to the vertex, while on the upper part of the back of the head are 

 indications of a postocular row of rather strong black bristles, and out on the back 

 of the head well away from the eyes are some more black 

 bristles ; in the female the pubescence is shorter and the black 

 bristles are more numerous and conspicuous ; back of the head 

 rounded out behind the eyes, mouth-opening large and long 

 being extended considerably forwards ; ocelli three. Proboscis 

 rather withdrawn but upturned and not extending up to the 

 antennae ; sucker-flaps large and ribbed ; palpi cylindrical, 

 rather knobbed at the tip, and conspicuously pubescent. Eyes 

 bare, touching in the male for a considerable space but in 

 the female widely separated ; facets hardly conspicuously con- 

 trasted in size. Antennse (fig. 318) porrect, approximated at 

 the base, rather long, but not longer than the head ; basal 

 joint long and cylindrical, not inflated, but bearing some long 

 pubescence on the basal two-thirds and some stifii" black bristles 

 on the apical part; second joint about a quarter the length of the first, and also 

 bearing shorter but more numerous bristles ; third joint divergent, about as long 

 as the first, and with an indistinct annulation near its base, bare of pubescence, and 

 ending in a short style which bears a very short thread-like apical filament. 



Thorax oval, densely pubescent in the male but with shorter more depressed 

 pubescence in the female ; strong black cheetotactic bristles are always present, of 

 which about four (3-6) are prtesutural, two supra-alar, one strong postalar, and one 

 or two pairs prsescutellar, but the pairs of prsescutellar bristles are liable to vary 

 in an irregular manner so that they may be asymmetrical. Scutellum semicircular, 

 with two pairs of conspicuous black marginal bristles ; metanotum small and 

 bare, rather concealed beneath the projecting scutellum. 



Abdomen conical and longer than the thorax, with seven or eight obvious 



segments in the male, but with the distinct eighth 

 segment in the female forming the basal portion of 

 the ovipositor ; hindmargins of segments usually 

 yellowish on just a marginal hem both dorsally and 

 ventrally ; pubescence dense and almost furry in the 

 male but with hairs of different lengths, and with 

 shorter usually adpressed pubescence on the basal 

 segments in the female, and in the latter sex the 

 pubescence on the fifth to eighth segments is short 

 and rigid (fig. 319). Genitalia of the male fairly dis- 

 tinct, but the ovipositor of the female (fig. 319) 

 and more produced and ending in a circlet of conspicuous thick black 



Fig. 



319. — Thcreva nohilitata ?. 

 End of abdomen. 



longer 



spines. 



Legs slender, and bearing abundant soft pubescence in addition to some black 

 bristles on at least the coxae and anterior femora. Bristles on the coxse about two 

 on the front, four on the middle, and one on the hind pair ; those on the anterior 

 femora usually (but not always) two or three (rarely one) beneath (or almost antero- 

 ventral) near the middle, and those on the hind femora forming an irregular antero- 

 ventral row of about seven bristles ; tibiae with rows of small bristles and with circlets 

 of spurs, but the rows on the anterior pairs do not extend to the base, and though 

 there are about three rows of three (3-6) bristles on the front tibiae, four rows of 

 about three (3-7) bristles on the middle tibiae, and four roAvs of about eight 

 bristles on the hind tibiae extending the whole length, yet the bristles vary in 

 both species and individuals ; tarsi normal, but with a few " touch-hairs _" beneath 

 the front pair, and with short strong black plantar bristles on the posterior pairs ; 

 there is a small process on the front of the hind coxae near the base, which is not 

 easily detected in the pubescence. 



Wings normal in venation ; fourth posterior cell usually closed but occasionally 

 just open in the female or in individual specimens though this cell is more or less 



2 M 



