1980] 
Evans, Matthews, & Hook — Pison in Australia 
225 
6.5-8 mm in length and are light brown in color, of thin, parchment¬ 
like material (Fig. 7). 
Pison marginatum Smith 
This species also made use of trap nests in the Canberra area during 
1969-70, but the three nests we found all occupied larger borings, 6-7 
mm in diameter. A nest collected near the Murrumbidgee River on 1 
February contained cocoons which gave rise to adults on 20 March, 
while a second nest collected in the same area on 7 March contained 
eggs and larvae on the prey and ultimately produced adult wasps the 
following September. A third nest, on Black Mountain, Canberra, 
contained cocoons when harvested 24 March and also gave rise to 
adults the following September. Thus there are evidently two 
generations a year in the Canberra area. 
The three nests had from 4 to 7 cells each, the cells measuring from 
12 to 19 mm in length and separated by mud partitions 1-2 mm thick. 
Two of the nests were closed off by thick mud plugs, 17-18 mm thick; 
the third had an empty vestibular cell 30 mm long, closed off by a thin 
plug which was recessed 7 mm from the bore opening. 
This last nest was abundantly supplied with small spiders, 5 to 9 per 
cell. Four of the cells contained eggs, in each case laid longitudinally 
on the abdomen of a spider close to the cell entrance, suggesting that 
it was laid on the last spider placed in the cell (Fig. 6). The following 
spiders were identified: 
ARANEIDAE: Gea theridioides (Koch)—7 99 
Araneus lutulenta (Keyserling)— 1 immature 
OXYOPIDAE: Oxyopes elegans Koch—1 9 
One cell from the Murrumbidgee River nest collected on 7 March 
had a small parasitoid larva feeding on the host egg (Fig. 3). We did 
not rear this successfully. Callan (1979) has reported the rhipiphorid 
beetle Macrosiagon diversiceps (Blackburn) as a parasitoid of the 
related species P. spinolae, and we suspect that the larva we observed 
was that of a rhipiphorid. The cocoons of marginatum measure 11-13 
mm in length and are of a darker shade of gray-brown than those of 
westwoodi, and the walls appear thicker and firmer (Fig. 9). 
Pison spinolae Shuckard 
This is a relatively large species of Pison which has been introduced 
from Australia into New Zealand, where it is especially common. 
