The pheromone first isolated in bark beetles and also produced by bull elephants is frontalin.
Frontalin is a naturally occurring terpenoid and acetal. In several bark beetles, including the southern pine beetle and western pine beetle, it functions as an aggregation pheromone, helping draw beetles together on suitable host trees. Its discovery in insects made its later occurrence in elephants especially striking.
Adult male Asian elephants release frontalin during musth, a recurring physiological state associated with heightened reproductive activity, aggression and mating readiness. Frontalin levels generally rise with age, and the chemical signal can help advertise a bull’s condition to females that are receptive.
A common mix-up is with muscone, civetone and androstenone. Those are also famous animal-associated odor compounds, but they are not the canonical answer to this elephant-pheromone question. Frontalin is unusual because the same named compound serves as a pheromone in both insects and elephants.