50 
Psyche 
[Vol. 87 
at Taperinha, near Santarem, Para, Brazil (2° 32'S, 54° 20'W) on 13 
November 1978. P. canadensis specimens were collected from both 
pre- and post-emergence nests. After fixing the wasps in Kahle’s 
solution, the sternites and attached tissue were removed and 
embedded in Spurr Low-Viscosity embedding media (Polysciences) 
following the methods of Spurr (1969). Sections 2/j thick were cut 
with a glass knife on a Porter-Blum-Ultra-Microtome MT-1 (Sorvall®) 
for examination with the light microscope. Staining was with 
Mallory’s Azure II-Methylene Blue (Richardson et al., 1960). 
For SEM preparations specimens were dehydrated in 100% 
ethanol and sonified. After air drying the tissues were coated with a 
thin layer of gold-palladium and examined with a JELCO JSM-U3 
scanning electron microscope at 20 kV. Images were recorded on 
Polaroid film (Type 55, P/N). 
Adult females of each species were dissected in order to estimate 
the number of gland cells in the terminal sternite. The number of cells 
in each gland was estimated by determining the length and width of 
the glandular mass by means of a filar micrometer eyepiece, dividing 
each by 0.025mm (approximate diameter of an individual gland cell), 
multiplying the two results and then multiplying by the thickness of 
the gland, in numbers of gland cells (determined from histological 
sections) (1.25 for P. fuscatus and 2.5 for P. canadensis). Although 
this estimate does not give an exact count of the number of gland 
cells, it does allow a comparison of the relative number of gland cells 
in the two species. 
Results 
6th Sternite. 
As in species studied previously, the anterior region of the terminal 
sternite of female P. fuscatus and P. canadensis bears a brush-like 
arrangement of dense hairs (Figs. 1 & 2). The brush is denser and 
more extensive in P. canadensis than in P. fuscatus. The cuticle 
underlying the brush is lightly sclerotized and translucent'(hyaline), 
but is not thinner than adjacent cuticle. The gland consists of two 
clusters of glandular cells (class 3 cells of Noirot and Quennedey, 
1974), one on each side of the brush and hyaline area; there art no 
gland cells directly beneath the brush (Fig. 3). Each gland cell is 
connected by a duct to the sternal surface (Figs. 4 & 5). The majority 
of the ducts run mesad from the gland cells to the brush (Fig. 6) and 
