1979] 
O’Neill — Behavior of Philanthus psyche 
27 
Mean distance intruder pursued by males (cm) 
INTRUDER o, 5 ~ g ro 04 
° o o O o § 
Philanthus psyche 
P. psyche Q 
P. psyche 2 w/prey 
Bembecinus nanus 
Eumenid wasp 
Microbembex spp. 
Bombyliid fly 
Parnopes edwardsii 
Bembix pruinosa 
Butterflies 
Podalc nia spp. 
Ammophila spp. 
Mutillid wasp 
Pompilid wasp 
Asilid fly 
igure 3 . Intensity of response (distance pursued) of male P. psyche for each 
species of intruder. Intruder species are on the horizontal axis, arranged from left to 
right in order of decreasing similarity to a conspecific female (see Table 1) 
flight seems to be the only distinctive aggressive male-male inter¬ 
action in P. psyche. 
A frequent response of a male to an intruder involved approach 
and/or pursuit of an insect passing through or near the territory 
Different insects were pursued different distances by the territorial 
males, some simply being approached with the male not leaving his 
territory. Others were pursued relatively long distances. The ques¬ 
tion arose that if there is a relationship between the distance pursued 
and the identity of the intruder, is the intensity of the male’s 
response (distance pursued) based upon the similarity of the in¬ 
truder to male or to female conspecifics (i.e„ is the response 
aggressive or an attempt at securing a mate, respectively)? In order 
