Psyche 
[March 
Figs. 1-3. Typical nests of Ammophila azteca (all from Jackson Hole, 
Wyo.) showing the three types of closures. Fig. 1. No. 2018, an empty nest 
closed with a single pebble and a small amount of sand. Fig. 2. No. 1993, a 
nest with a single caterpillar bearing the egg, showing a typical temporary 
closure. Fig. 3. No. 1996, a fully provisioned nest which had received the 
final closure. 
scatters the soil rather widely. In any case it weathers away in a few 
days, and some of the soil may be used in closures. 
There appears to be considerable variation in the distance the 
female flies with the soil, and consequently the distance from the nest 
entrance the mound accumulates. In Jackson Hole, most mounds 
were only a few cm from the entrance (2-6, rarely up to 20). Hicks 
(1935) observed very similar digging behavior in Colorado, but he 
found that the soil was carried a considerable distance from the nest, 
in one case four feet (1.2 m). Hicks timed several females and found 
that they carried from five to seven loads per minute. “One load”, 
he reports, “was so large and heavy that the wasp was not able to fly 
with it after a typical and normal fashion and only reached the refuse 
spot by short flights and hops.” Great variation in the distance the 
soil is carried was noted by Hicks (1932) in another species, A. 
aherti. 
Burrow diameter in A. azteca is about 5 mm; the terminal cell is 
horizontal and has a diameter of about 10 mm, a length of 20-25 mm. 
All burrows at Jackson Hole were vertical or very nearly so; they 
varied in length from 3 to 6 cm, nearly all of them measuring between 
4 and 5 cm (Figs. 1-4). The single nest excavated at the Great Sand 
Dunes, Colorado, was very similar, having a vertical burrow 3.2 cm 
long reaching a horizontal cell 2.2 cm long. The nest from Yellow- 
stone was very similar in size but was dug into the sloping of a foot- 
path and had an oblique burrow (Fig. 5 in Evans, 1963). 
Closure of the nest. — As in many species of this genus, three types 
of closure' can be distinguished : initial closure of the empty nest, 
temporary closures during provisioning, and final closure of the fully 
provisioned nest. The initial closure consists of a single pebble or 
hard lump of earth which is placed in the burrow entrance with the 
