1965] Evans — Ammophila azteca II 
Both males and females were seen frequently on the flowers of 
Solidago and Erigeron growing in and near the nesting area, and it is 
probable that they obtain nourishment throughout the season from 
this source. Early in the season males were observed in considerable 
numbers flying close to the ground in the nesting area. On one 
occasion three males were seen digging intermittently and trying to 
enter a vertical hole, presumably in anticipation of the emergence of 
a female. I did not observe mating, chiefly because most of my studies 
were made a week or more after nesting had begun, when most 
mating had probably ceased and the males were declining in numbers. 
Mating in several species of Ammophila has been well described (e.g., 
Baerends, 1941; Olberg, 1959). 
As compared to other wasps in this area, Ammophila azteca made 
its appearance rather early each morning (0830-0900) and was 
active until late in the afternoon (1630). Active wasps were often 
noted in partial shade or during periods of partial cloudiness, but they 
invariably disappeared when the sun was heavily obscured for more 
than a few minutes. I did not discover where they went during these 
inactive periods or at night. Hicks (1935) found a female of this 
species “sleeping” on a stem in late afternoon, presumably solitarily. 
The wasp held her body at nearly a right angle to the stem, grasping 
the support with her mandibles and some of her legs. A number of 
species of Ammophila are known to sleep in somewhat this manner, 
often more or less gregariously (e.g., Evans and Linsley, i960). 
Digging the nest. — Nests appear to be started at any time of day, 
but more especially in the mid-morning hours or late in the afternoon. 
Digging females periodically produce a “chirping” sound as they 
break through the soil with their mandibles. One female starting a 
new nest dug 1 cm in 13 minutes, the second cm in another 7 minutes; 
she completed the burrow and cell in a total of 58 minutes. This 
female had previously been digging at another point 10 cm away, but 
she abandoned this nest after apparently striking a stone; the aban- 
doned burrow was left open. 
When the wasp has loosened a small lump of earth, she holds it 
between her mouthparts and front legs, backs from the burrow, rises 
into the air a short distance, and with a slight jerk flings it onto the 
ground. She may fly in any direction from the entrance, but most 
wasps make the majority of flights on the same side, such that the 
earth comes to form a diffuse but discernible mound in the form of a 
small arc. The mound is rarely more than 0.5 cm deep, and varies 
from 2 to 4 cm wide by at least twice that long, although its borders 
are ill-defined. In some nests no mound can be seen, as the female 
