1988] 
Topoff & Greenberg — Polyergus 
83 
each queen into head, thorax and abdomen. These three body parts 
were put into separate vials and taken to Polyergus nests. We then 
used the blunt end of a small plastic paintbrush to squash the body 
part on a small rock near a raiding swarm. For three tests (each with 
a different colony), males responded to the squashed heads by run- 
ning in circles and mounting each other. No males appeared when 
we crushed the thorax or abdomen. 
Laboratory Studies 
Methods 
To determine the source of the queen’s sex pheromone, glands 
dissected from the heads of P. breviceps queens were presented to 
males confined in a laboratory enclosure. Because of its large size, 
the primary candidate for the sex attractant was the mandibular 
gland and its reservoir. Dissections were done in a wax-lined petri 
dish, filled with mineral oil (to retard evaporation of the volatile 
pheromone). First, the cuticle around the queen’s mandible was cut 
(or removed). By holding the queen’s head firmly with forceps and 
then gently pulling on the mandible, we were able to remove the 
mandibular gland. Only those preparations containing the intact 
glandular reservoir were used for bioassays. As a control, we used 
the remains of the head after the mandibular glands were removed. 
The behavioral tests were conducted with seven Polyergus males, 
confined together in a plastic box (16.5 cm X 12.5 cm X 6.5 cm 
high). The lid of the box had a large opening (10 cm X 8 cm), 
covered by a mesh screen. Additional ventilation was provided by 
holes (2.5 cm diam) cut into opposite ends of the box. Rubber 
tubing (5.0 cm long and capped with nylon mesh) was placed tightly 
into these holes. All tests were conducted under artificial light, both 
to maintain the experimental chamber at 29° C, and to inhibit the 
males’ typical approach response to the day-time sky. At the start of 
a test, one mandible with the attached gland and reservoir (or 
remaining head) were held in forceps near the rubber tube’s outer 
opening. A constant current of air through the box was provided by 
a fan placed 2 m from the chamber. After recording the number of 
active males during a 10-s interval, each preparation was crushed 
with the forceps. We then recorded the number of males active 
during a second 10-s interval, after which the preparation was 
removed. In all cases, we recorded a response as positive if the males 
