Gas chromatographic analysis of the volatile terpenes of the wood oleoresin of maritime pines showed that the relative proportions of terpenes within the same tree did not vary according to sampling height and date. Pruning and tree vigor did not affect terpene profiles, but oleoresin composition varied widely from tree to tree. The trees attacked by Dioryctria sylvestrella contained a significantly higher percentage of limonene, longipinene, and copaene, and a discriminant analysis, using the relative percentage of six terpenes, significantly separated infested and uninfested trees. The olfactory sensitivity of adult moths to a series of 20 volatile chemicals, including maritime pine oleoresin components, was evaluated with the electroantennogram method. Both sexes were sensitive to monoterpenes, oxygenated terpenoid compounds, and oleoresin samples. The use of terpenes as host attractants and biochemical markers for resistance to D. sylvestrella is discussed.