164 
Psyche 
[June-September 
female was apparently not receptive and no copulations were 
observed. Evans (pers. comm.) suggests that Crabro females recog¬ 
nize their species specific pattern when their eyes are covered by 
these distinctively marked male tibial shields. Light passing through 
such thin, partially transparent shield cuticle could transmit a char¬ 
acteristic pattern which might alter female receptivity. 
Several cocoons of C. argusinus were obtained during the course 
of this work and one of them is shown in Fig. 8. Developmental data 
were obtained for a few cells transferred to rearing tins during the 
spring of 1978. One egg laid April 22 developed to mature larva 
which spun its cocoon on April 26-27 and emerged as an adult on 
May 20. It seems likely that there is at least a partial second genera¬ 
tion in the spring. During our visit in late April nesting seemed to be 
at a peak at all localities. The boiler site colony was still active on 12 
May when we returned, but activity ceased about 20 May and 
Oxybelus sericus Robertson became the dominant species at that 
site. The last nest was dug on 10 June 1978 at the Wamassee Creek 
site where only a few active nests remained at that date. 
Searching females were repeatedly observed to dart at the sides of 
depressions in the substrate. At the road site females showed a 
decided bias for nest sites situated in depressions as compared to 
surrounding flat sand. For example, a horse hoof print had 4 closely 
spaced nests initiated in the angle formed by the sides and base of 
the print within 24 hr. Such a close spacing of nests is unusual. 
Evans (1960) never found active nests closer than half a meter. His 
study site was an erosional bank of a draw, most similar to our 
Figure 8. Cocoons of Crabro argusinus. Length of right cocoon is 7 mm. 
