34 
Psyche 
[March 
simultaneously. The significance of this “inspection” behavior may 
be protection against predators and parasites by enchancing the likeli- 
hood that an intruder will be encountered before endangering the 
nest. 
In one instance a small beetle larva was deliberately placed on 
the nest. Its movements quickly attracted the two wasps inside the 
n,est. At the first encounter the wasps attempted to grasp the in- 
truder in the mandibles but were repelled. There followed a period 
of extensive rapid crawling over the nest during which the wasps 
encountered the intruder several times but failed to successfully re- 
move it. After about 7 minutes, the larva dug into the loose material 
in the bottom of the nest, and about 2 minutes later the wasps re- 
turned to the inside of the nest and no longer seemed excited. The 
following day the beetle larva emerged from the nest and again 
created considerable excitement until it again burrowed inside the 
nest about 4 minutes later. When the nest was collected that after- 
noon, the beetle larva was found inside. On another occasion, a 
female braconid wasp parasite (see following section) was observed 
to crawl down the pedicel and then run quickly onto the nest sur- 
face. In less than two seconds, a Microstigmus emerged from the 
nest, presumably stimulated by the braconid’s movements. In circling 
the nest it encountered the braconid almost immediately, causing the 
parasite to fly. 
“Maintenance” trips took three forms. One type involved carry- 
ing small chunks of fibrous material from the interior of the nest to 
the outside, where they were dropped. Typically this behavior oc- 
curred in spurts, several such pieces being carried out over a three 
or four minute period. The material to be discarded was carried in 
the mandibles and usually down to the bottom half of the nest. 
Then, while standing on the hind two pairs of legs, the wasp re- 
moved the material from its mouthparts with the fore tarsi and the 
material floated away. 
Explanation of Plate 3 
Fig. 6. Dorsal view of M. comes ( $ ) apical tergite, treated with 10% 
KOH. Note cluster of blunt-tipped setae (sb) at apex; cuticular portions of 
associated gland (gl) are also visible. Central “line” (arrow) is edge of 
tergite, bent back upon itself. 
Fig. 7. Cuticular vesicular organelles (VsO) and associated tubules 
(Tu) isolated from glands of apical tergite by KOH treatment. Note the 
indistinct peripheral fringe swellings (PF) covering surface of each or- 
ganelle. 
