143 
labor, he often guards the entrance to one or two nests. Howes 
further observed that 7. leucotrichium, which nests in reeds 
which are open from below, stuffs the cells with long-legged 
spiders so that these jam and do not slip down and out. The 
genus Pison includes rather stout little wasps sometimes building 
in ready-made cavities, tubes, between the leaves of books, etc., 
and, again, forming delicate, filagreed oval cells in the angles of 
walls, or freely sus- 
pended from _ roots, 
etc., as represented in 
the many - celled nest 
in Fig. 72. This nest 
produced a bombliid- 
fly, a patasite’ ot 
wasps. Pison argen- 
tatum 1s the common- 
Esty Species wat) mzos 
Banos. It preys on 
spiders. 
In my _ experience 
the tropical members 
of the genus Trypoxry- 
lon are more particu- 
lar Sthan’ the  Sceli- 
phronini (with whom 
they often associate in 
gathering mud in the 
Philippine forests) as 
to the kind of spider 
used” Storestore their 
ig. 72. Nest of Pison sp. suspended from cells” he sattids’ or 
rootlets, X 2/3. jumping spiders are 
one of their favorites, 
and these may be of proportionally large size, so that sometimes 
but two or even one suffices for a single wasp grub. Like the 
adult, the larva and pupa and cocoon are slender, the last resem- 
bling somewhat that of the Sceliphronini. 
Ashmead (1894) records three species as supplying their nests 
with Aphids. 

Trypoxylon elongatum Ashmead. 
Length 15-21 mm.; black and red; very slender. 
This attenuated forest insect (Fig. 73), in company with other 
10 
