1979] 
O’Neill — Behavior of Philanthus psyche 
23 
recording the location of plants on which males “scent marked” 
around the territory and perching points on the sand and marking 
off the area which they encompassed, a rough measure of territory 
size can be made. These areas visibly coincide with the bare areas of 
sand occupied by males in the field. (If we chose, instead, to take the 
boundary of the territory as the maximum distance from its center 
at which a male will sight and approach a passing insect, the above 
measurement would be only a slight underestimate of functional 
territory size.) The mean size for twelve territories was 0.17 m 2 
Figure 2. Map of 3 m 2 area in which most observations were made in 1977. 
Dotted lifies indicate the area encompassed by all marked plants and/or perches of 
male(s). For several territories it was necessary to record, on two separate days, 
plants marked by different males. Solid circles and ovals indicate plants that were 
marked by males. N indicates a 1 nest entrance. 
