PSYCHE 
VOL. LI 
Mar.-June, 1944 
Nos. 1-2 
HOW ODYNERUS SUSPENDS HER EGG 
By Carl G. Hartman 
Department of Zoology and Physiology 
University of Illinois, Urbana, Illinois 
So far as the writer is aware it was he and his sons, Philip and 
Paul, amateur entomologists, who first witnessed a Eumenid wasp 
expel her egg and hang it from the ceiling of her nest — or rather 
suspend it and then expel the egg, for, as a matter of fact, the 
thread is made first. Dame Fortune was with us further in that 
the very first time we witnessed the act we had the movie camera 
set up, loaded with Kodachrome, and so secured a motion picture 
of oviposition. 
For some forty years, on numerous occasions, I have amused 
myself and bored tolerant friends by attracting certain solitary 
bees and wasps ( U tube fillers”) to my window-sill by setting out 
tubes of various diameters suitable for their occupancy. Try- 
poxy Ion and Odynerus were sure to be there, also small bees as 
well as the larger Megachile, the leaf cutter. The last mentioned 
proved especially popular with the amateur naturalist. The 
method most often employed was that well described and figured 
by Savin (Natural History, 1922). This method consists essen- 
tially of screwing together two smooth-faced boards and boring 
holes of various diameters down the surface of junction. By re- 
moving the screws the work of insects could readily be laid bare. 
Bamboo tubes and even rubber tubing were also set out, but the 
latter does not favor the survival of the wasp grubs. In vacation 
time of 1941, however, at Bethlehem, Connecticut, all energies 
were devoted to watching and photographing the insects as they 
worked in glass tubes. No better means can be imagined for pry- 
ing into the insects’ domestic activities than by inducing them to 
live in glass houses ! In this the insects proved most cooperative. 
