1974 ] Evans , Matthews J & Callan — Rubrica surinamensis 349 
antennal papilla and almost total lack of body setae and spinules 
suggest Steniolia. On the whole, larval characters suggest that 
Rubrica may not be as closely related to Bembix and to Stictia as 
might be assumed on the basis of adult structure. 
Discussion 
The somewhat isolated position of Rubrica among the genera of 
Bembicini is suggested not only by larval characters but by a number 
of behavioral peculiarities, of which the following five are especially 
noteworthy. 
( 1 ) Females make a small pile of earth and pebbles over the nest 
entrance, to which they return and use as a perch from time to time 
when not engaged in other activities. Members of other genera that 
spend inactive periods away from the nest tend to return occasionally, 
but usually hover briefly over the entrance (e.g. Steniolia). 
(2) Although R. surinamensis is a predator on flies, there are 
several records of females taking Lepidoptera (Hesperiidae, Pyra- 
lididae) and one record of a dragonfly being used as prey (Libel- 
lulidae). Evidently the females do not discriminate as sharply as 
do most other Bembicini. For example, the many hundreds of records 
for North American Bembix include no non-dipterous prey (Evans, 
I 957 > 1966). On the other hand, Janvier (1928) found that the 
fly predator Zyzzyx chilensis (Eschscholz) occasionally takes a skipper 
(Hesperiidae). Manfredo A. Fritz has informed us (in litt.) that 
he has taken skippers from the nests of the fly predator Trichostictia 
guttata (Taschenberg) in Argentina. It should be noted that Lepi- 
doptera form the normal prey of members of the genera Edit ha and 
Stictiella. Use of Odonata as prey is more unusual, but two Aus- 
tralian species are now known to prey on damselflies, at least one of 
them also on flies (Evans and Matthews, 1973). Evidently there is 
enough similarity in the flight characteristics of Lepidoptera and 
Odonata to those of Diptera that the switch-over is not difficult. 
Lin (1971) recently discovered that some members of an aggre- 
gation of 2000 females of Stictia Carolina Fabricius in Oklahoma 
preyed not only upon skippers but upon small brown cicadas (Ho- 
moptera), although flies constitute the usual prey of this species. 
He postulated that competition for food in this dense population 
caused females to accept unusual prey. 
(3) Cell cleaning by flying from the nest and dropping the debris 
some distance away is well marked in Argentinian populations, but 
it has not been observed in northern South America. It is perhaps 
