1983] 
Frolich & Parker — Eumegachile 
201 
a plug took about 7 hours to complete. Approximately 15 Oeno- 
thera, 15 soil, and 3-4 large oval leaf collecting trips were required 
per partition. Plug construction required roughly twice those num- 
bers. Collection of oval leaf pieces took longer than collection of 
Oenothera strips (x = 1 min. 23 sec., sd = 49 sec. vs x = 40 sec., sd = 
9.4 sec.) and soil collecting trips were shortest of all (x = 22.5 sec., sd 
= 7.7 sec.). 
In most cases females constructed nests in hollow sticks. How- 
ever, when undrilled sticks, with shallow (5 mm) starter holes drilled 
in the side, were placed in the greenhouse for use by another bee 2 
E. pugnata widened the cavities and nested therein. 
Development 
Egg Hatching. The egg, which was attached to the provision by 
its posterior Va, was opaque when deposited but gradually became 
translucent as it developed. It measured \-\V 2 mm wide anteriorly 
and posteriorly, 3-4 mm in length, and was straight (Fig. 3). 
Embryogenesis took an average of 5.1 days at 30° C (Table 1) and 
some structures became grossly visible through the chorion approxi- 
mately 1 day before eclosion. 
Eclosion usually took from 10 to 12 hours and became evident with 
the appearance of a clear fluid-filled area in the region of the poste- 
rior attachment. At this time the dorsal vessel, spiracles and major 
tracheal branches were visible. As the fluid increased in the poste- 
rior pole the embryo exhibited undulating waves that passed from 
anterior to posterior and perhaps aided in concentrating the fluid in 
the posterior region. Thus, the chorion was stretched very tightly 
over the head of the enclosed embryo. After fluid disappeared from 
the posterior pole the embryo appeared to remain quiescent for a 
short time. Fluid then began to collect at the anterior pole of the 
egg, accompanied by undulating waves moving in the opposite 
direction (posterior to anterior). As the chorion became tightly 
stretched over the posterior embryo a longitudinal-lateral split in 
the chorion became visible at the level of the spiracles. This rupture 
divided the chorion into upper and lower halves. As the pressure 
and peristaltic waves receded the lower half of the chorion slipped 
from the larva and came to lay directly between it and the pollen 
