The Dufour glands of P. longicornis contain a group of simple 2-ketones and alkanes, typical of the Dufour glands of many formicine ants. The principal component of the secretion was 2-tridecanone, followed by undecane, 2-pentadecanone and tridecane, with traces of decane, 2-dodecanone, 2-tetradecanone, ethyl phenylacetate and butyl phenylacetate. The venom gland contained, as expected, formic acid. The mandibular glands contained very small amounts of 2,6-dimethylpyrazine, trimethylpyrazine, 3-ethyl-4-methylpentan-1-ol (but not found in all samples), and 4,5-dihydroxydecanoic acid gamma-lactone. Ethyl and butyl esters of the common fatty acids were found in heads and abdomens.