OBSERVATIONS ON THE NESTS AND PREY OF 
EUMENID WASPS (HYMENOPTERA, EUMENIDAE)* 
By Howard E. Evans 
Department of Zoology & Entomology 
Colorado State University 
Fort Collins, Colo. 80523 
The recent development of the techniques of trap-nesting have 
added greatly to knowledge of the biology of twig-nesting Eumeni- 
dae (e.g. Cooper, 1953, 1955; Krombein, 1967; Fye, 1965). How- 
ever, only scattered information is available on species that nest in 
the ground or make free mud nests. Recent papers describing the 
behavior of North American ground-nesters include two on species 
of Stenodynerus (Evans, 1970; Clement, 1972) and two on species 
of Pterocheilus (Grissell, 1975; Evans, 1977). The present paper 
includes notes on a ground-nesting Pseudepipona and an aerial- 
mud-nesting Parancistrocerus as well as on a mud nest built by a 
species of Euodynerus in a burrow dug by a sphecid wasp. This 
last example is described first. 
Euodynerus auranus (Cameron) 
Several females of this species were seen in a large blow-out in a 
dune area near Roggen, Weld Co., Colorado, on 2 August 1977. 
This blow-out was a major nesting site for the sphecid wasps 
Bembix pruinosa Fox and Philanthus albopilosus Cresson, but it 
seemed an unusual habitat for a eumenid. When a female Euody- 
nerus auranus was seen to plunge into an open hole in sloping sand 
carrying a small caterpillar in her mandibles, she was captured and 
the hole excavated. 
The burrow was apparently an abandoned, incipient nest of 
Bembix pruinosa, being of the form characteristic of that species 
and having a mound of sand on the down-slope side. The burrow 
terminated 15 cm from the entrance, at a depth of 5.5 cm from the 
surface directly above. In the bottom of the burrow was a single 
mud cell, open facing the burrow, measuring 9 mm in diameter 
* Manuscript received by the editor January 26, 1978. 
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