Abstract The four monoterpene compounds [1, (+)- cis-2-isopropenyl-1-methycyclobutaneethanol; II, ( Z)-3,3-dimethyl-Δ 1, β -cyclohexaneethanol; III, ( Z)-3,3-dimethyl-Δ 1, α -cyclohexaneacetaldehyde; and IV, ( E)-3,3-dimethyl-Δ 1, α -cyclohexaneacetaldehyde] which comprise the pheromone of the male boll weevil, Anthonomus grandis, were determined daily throughout the lifespan of the insect by GLC analysis of the whole body and the frass. The total content of the components in the male is never greater than 210 ng, the average content in the frass produced during 1 day is 1268 ng, and the lifetime production is at least 40,000 ng. The ratio of the four components in frass is 6 : 6 : 2 : 1/I : II : III : IV. None of the four components was found in females, but female frass contained traces in three instances. These data can be used to compare the potential attractancy of insects from various geographical areas, at different seasons, in different nutritional states, and after chemosterilization. Such differences in potential insect attractiveness could be crucial to effective large-scale control programmes.