Cuap. VIII. PELOPAUS WASP. 199 
Peruvian borders, and forms part of the great Tabatinga marl deposit. 
To enable the vessels to stand the fire, the bark of a certain tree, called 
Caraipé, is burnt and mixed with the clay, which gives tenacity to the 
ware. Caraipé is an article of commerce, being sold, packed in baskets, 
at the shops in most of the towns. The shallow pits, excavated in the 
marly soil at Mahica, were very attractive to many kinds of mason bees 
and wasps, who make use of the clay to build their nests with. I spent 
many an hour watching their proceedings ; a short account of the habits 
of some of these busy creatures may be interesting. 
The most conspicuous was a large yellow-and-black wasp, with a 
remarkably long and narrow waist, the Pelopzeus fistularis. It collected 
the clay in little round pellets, which it carried off, after rolling them 
into a convenient shape, in its mandibles. It came straight to the pit 
with a loud hum, and on alighting, lost not a 
moment in beginning to work; finishing the — 
kneading of its little load in two or three \ 
minutes. The nest of this species is shaped 
like a pouch, two inches in length, and is 
attached to a branch or other projecting object. 
One of these restless artificers once began to 
build on the handle of a chest in the cabin 
of my canoe, when we were stationary at a 
place for several days. It was so intent on 
its work that it allowed me to inspect the 
movements of its mouth with a lens whilst 
it was laying on the mortar. Every fresh 
pellet was brought in with a triumphant song, 
which changed to a cheerful busy hum when 
it alighted and began to work. The little ball 
of moist clay was laid on the edge of the cell, 
and then spread out around the circular rim, 
by means of the lower lip guided by the mandibles. The insect 
placed itself astride over the rim to work, and, on finishing each addition 
to the structure, took a turn round, patting the sides with its feet inside 
and out before flying off to gather a fresh pellet. It worked only in 
sunny weather, and the previous layer was sometimes not quite dry 
when the new coating was added. The whole structure takes about a 
week to complete. T left the place before the gay little builder had 
quite finished her task: she did not accompany the canoe, although 
we moved along the bank of the river very slowly. On opening closed 
nests of this species, which are common in the neighbourhood of 
Mahica, I always found them to be stocked with small spiders of the 
genus Gastracantha, in the usual half-dead state to which the mother 
wasps reduce the insects which are to serve as food for their progeny. 
Besides the Pelopzeus there were three or four kinds of Trypoxylon, a 
genus also found in Europe, and which some Naturalists have supposed 
to be parasitic, because the legs are not furnished with the usual row 
of strong bristles for digging, characteristic of the family to which it 
belongs. The species of Trypoxylon, however, are all building wasps : 
two of them which I observed (T. albitarse and an undescribed species) 

Pelopzeus Wasp 
building nest. 
