42 
Psyche 
[March 
nest (72-1) had no visible oocytes, suggesting that they were newly 
emerged, possibly offspring from that nest. However, in contrast 
to most Hymenoptera, wing and mandible wear in M. comes seemed 
to be non-existant, and hence of no use as an indicator of the relative 
ages of the wasps. Relative pigmentation was a potential indicator 
of age, and many adults appeared to be in a teneral condition^ but 
such a character is difficult to quantify. 
Thus, if social behavior is defined as activity of an individual 
benefiting the young of another of the same species (Richards, 1965; 
West, 1967), Microstigmus comes can certainly be regarded as a 
truly social sphecid wasp. Most notable in this regard are the reg- 
ular occurrence of more than one adult in a single nest and the 
demonstration of parental care (provisioning and defense) of brood 
by more than one adult female. Even if the more stringent criterion 
of sociality, that of reproductive dominance (division of labor) is 
employed, the data are suggestive that this is the case. Why Micro- 
stigmus seems to have gone so far along the road to sociality is not 
entirely clear. If the theory of Hamilton (1964) is correct, a 
fact of potential significance in the social evolution of M. comes 
Fig. 10. Freshly provisioned cell of M. comes showing spherical food 
mass of Collembola and egg. (Photo by C. W. Rettenmeyer.) 
