Naval stores production is based upon exploiting the terpene chemical defense system of the pine tree, which protects against wood-decaying fungi and insect pests such as bark beetles (Dendroctonus Ips sp.). […] Pine oleoresin is a complex mixture of about 30 to 50 different terpene molecules, chiefly composed of diterpene resin acids and monoterpene essential oils, which impart different physical and biotic properties (Zinkel and Russell 1989).
Source: wiktionary