36 
Psyche 
[March 
Two other types of “maintenance’ ’ involved work on the exterior 
of the nest or pedicel. In one the wasp worked on the nest proper, 
removing numerous small pieces of nest material from the surface 
with the mandibles and discarding them in the manner described 
above. In one such case, a wasp pulled off 37 pieces of nest in less 
than eight minutes. The third variation of “maintenance” behavior 
consisted of work primarily on the pedicel or about the nest entrance. 
When on the pedicel the wasp repeatedly crawled up and down it 
in a spiraling manner^ with the body axis roughly perpendicular to 
the nest pedicel. Here the tip of the abdomen was used extensively, 
often vigorously stroking or tamping the substrate, suggesting that 
the setal brush and associated gland may function in this activity. 
This latter behavior was noted primarily in the early morning, and 
excursions often lasted 10 or more minutes. 
PARASITISM 
Nine cells in five nests were found to be parasitized by the braconid 
wasp Pleterospilus microstigmi. This wasp was first described by 
Richards (1935) from M. theridii nests on Trinidad, and my speci- 
mens have been compared with the type in the British Museum by 
G. E. J. Nixon. While no other parasites of M. comes were found 
in Costa Rica, Myers (1934) records a pteromalid wasp as a fre- 
quent parasite in M. theridii nests from Trinidad but does not men- 
tion any braconid parasites. 
The parasitized nests contained six pupae, two larvae and an egg. 
Adults subsequently emerged from some pupae. While the larvae and 
egg could not be positively identified, there seems little doubt that 
they were braconids. The egg was found attached to the ventral 
surface of a mature Microstigmus larva between the head and thorax. 
It measured 0.4 mm long and O.i mm wide at the middle, and was 
slightly tapered at one end. The larva was distinguished by the 
presence of two prominent tubercles dorsally. An opaque white cocoon 
was spun by the parasite, usually near the bottom of the cell. 
Adult H. microstigmi females were seen at the wasp nests on six 
occasions and probable oviposition was observed once. On this oc- 
casion, the braconid crawled slowly around the nest with the wings 
held vertically over the thorax for approximately 10 minutes. During 
this time she inserted her ovipositor completely into the nest several 
times, usually just in and out quickly (about 2 seconds). Whether 
these represented probes or repeated actual ovipositions is unknown. 
Eventually she left the nest, and flew slowly along the undersides 
of two other leaflets of the same leaf, apparently searching for other 
