Foraging workers of Formica planipilis and Pogonomyrmex salinus were collected at various distances from their colony by pitfall traps in the former species and by catching workers recruited to food at known locations in the latter. In F. planipilis the number of larger workers increased in proportional representation to distance from the nest. Larger workers also weighed relatively less with distance from the nest, indicating that energy or water allocated for maintaining all foragers is patterned such that resource loss with forager mortality is minimized. However, the smallest size class involved in foraging shows the opposite pattern, with heavier individuals being found farther from the nest. Thus, it is possible that smaller size classes function as mobile reserves of energy or water to maintain foraging activity of larger classes at a distance from the colony. In P. salinus all sizes of workers were equally likely to be found at any distance. Foragers weighed significantly less than mound workers of the same head size, again suggesting resource conservation in provisioning foraging workers. Differences in patterns of energy allocation to foragers are discussed relative to the species' ecologies.
"Patterns of energy allocation within foragers of Formica planipilis and Pogonomyrmex salinus,"
Western North American Naturalist: Vol. 62
, Article 6.
Available at: http://scholarsarchive.byu.edu/wnan/vol62/iss2/6