SIMULTANEOUS CARE OF MORE THAN ONE NEST 
BY AMMOPHILA AZTEC A CAMERON 
(HYMENOPTERA, SPHECIDAE) 1 
By Howard E. Evans 
Museum of Comparative Zoology 
In attempting to trace the origin of social behavior among wasps, 
in his Social Life Among the Insects (1923), William, Morton 
Wheeler selected Arnmophila as “a paradigm of the whole group of 
Sphecoids and solitary Vespoids”. Were he alive today, and able to 
utilize all the considerable knowledge of this genus gained in the last 
three decades, it seems likely that he would embrace Ammophila even 
more enthusiastically as a paradigm not only of the solitary wasps 
but of several preliminary stages in the origin of sociality. 
It has been shown by Evans (1958, 1959) and by Powell (1964) 
that the North American species of this genus which have been 
studied can be arranged in series as follows: (1) strictly solitary 
species which utilize a single large caterpillar per nest, (2) species 
which mass-provision with two to several small caterpillars, (3) 
species in which provisioning is commonly “delayed” such that the 
last prey is brought in after the egg has hatched, and (4) species 
employing progressive provisioning regularly. Several other aspects 
of behavior are roughly correlated with this progression : for example, 
species using smaller caterpillars usually carry the prey in flight, and 
these same species generally carry the soil of excavation away from 
the nest in flight. Also, most records of gregarious nesting pertain to 
species employing progressive provisioning. 
It is apparent that the European species can be arranged in a very 
similar series (Adriaanse, 1947; Teschner, 1959). One European 
species, A. puhescens Curtis, illustrates still a fifth stage in this 
ethocline: the female maintains two or three nests at one time, 
remembering the location of each of them accurately and behaving in 
accordance with the status of the egg or larva in each nest as deter- 
mined during frequent inspections (Baerends, 1941). Simultaneous 
care of more than one nest is otherwise virtually unknown among 
digger wasps, although a few species of Bembicini which make more 
than one cell per nest are reputed to begin provisioning a second cell 
Supported by a grant from the National Science Foundation, no. G17497. 
Most of the studies reported here were conducted at the Jackson Hole 
Biological Research Station, Moran, Wyoming. 
Manuscript received by the editor January 5, 1965 
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