The anatomical source of the trail pheromone in the black carpenter ant, <I> Camponotus pennsylvanicus </I>, was investigated by presenting workers with crude or synthetic hindgut extracts to test for attractancy and trail-following behavior. Chemical analysis was used in conjunction with behavioral bioassays to detect and identify volatiles from the rectal sac, poison, and Dufour's glands. The rectal material was also examined to determine levels of total nitrogen and identify metabolites in relation to other solid material present. Under laboratory conditions, foragers demonstrated a significant level of attraction to a combined Dufour's gland, poison gland, and rectal sac extract. No response was observed to synthetic compounds (formic acid and saturated hydrocarbons) from the poison or Dufour's gland. Two volatiles, n-undecane and n-tridecane, were identified from the Dufour's gland. Fatty acids and esters were found to be ubiquitous in the Dufour's and poison glands. Palmitic acid was identified in the poison gland. A compound described as a component of the trail pheromone in <I> Camponotus atriceps </I> (3,4-dihydro-3,5-dihydroxy-6-methyl-pyran-4-one) was identified in the rectum, but was not verified behaviorally as being part of the trail pheromone for <I> C. pennsylvanicus </I>. Trail following was not elicited from any of the rectal sac extracts. Dry weight analysis determined that the rectal material was only 14% solid material and total nitrogen levels were estimated at 19.2 ± 2 ug/mg of ant feces. Most of the components contributing to the total nitrogen excreted were left unidentified, but ammonia (2.7 ± 1.2 ug/mg), two tryptophan intermediates (kynurenic and xanthurenic acid) and one pteridine (biopterin), were identified. / Master of Science