234 
Psyche 
[September-December 
failed to note any “ergatoids such as occur with European H. sub- 
laevis. ” Nevertheless, Creighton (1950, p. 281), comparing H. amer- 
icanus with H. canadensis and H. sublaevis, stated that in ameri- 
canus “the ergatoid female is rarely produced.” 
In a recent study (Buschinger & Alloway, in press), we demon- 
strated that in all probability there are no ergatoid queens at all in 
H. canadensis. In contrast, although “normal” full queens occur 
occasionally in H. sublaevis, the usual reproductive female in this 
species is an ergatoid form which closely resembles the worker caste 
in its external morphology. Moreover, polymorphism among re- 
productive females is genetically mediated in H. sublaevis (Busch- 
inger, 1975, 1978, in press). Thus, the main objective of the present 
study was to determine whether ergatoid queens analogous to those 
found in H. sublaevis occur in H. americanus and, if so, what role 
they play. We especially wondered whether they might be the usual 
reproductives in the numerous “branch colonies” that lack a dealate 
full queen. 
Material and Methods 
Colonies of H. americanus were collected from various localities 
in the regional municipalities of Halton and Peel in southern On- 
tario, Canada. A few additional colonies were found near Cleve- 
land and Ashtabula, Ohio, in the United States. Most of the col- 
onies were nesting in old hollow acorns and hickory nuts lying on 
the ground. The colonies were removed from their nests using an 
aspirator either immediately in the field or later in the laboratory. 
Colonies whose broods consisted only of larvae and prepupae at 
the time of collection were kept alive in the laboratory for a few 
weeks to determine the sex and caste of the Harpagoxenus pupae 
that were produced. Some of the Harpagoxenus queens, all inter- 
morphs, and most of the Harpagoxenus workers were dissected 
using a method which we have described fully elsewhere (Buschinger 
& Alloway, in press). 
Results 
1. Population data. 
No effort was made to determine the ratio of Harpagoxenus to 
host-species colonies or the number of colonies per unit of area. 
Both variables fluctuate widely and depend upon a large number 
