Nymph and adult populations of Diclidophlebia eastopi Vondráček and D. harrisoni Osisanya were counted weekly on 3- or 4-year-old trees, Triplochiton scleroxylon, in Nigeria during 1966–71. D. eastopi showed successively larger peaks in late January or early February, mid-August, and early or mid-September; the smallest populations were in mid or late March. D. harrisoni showed peaks in February, late July or early August, and late October or early November, the second peak being the largest. Multiple regression analysis of Diclidophlebia populations against rainfall, saturation deficit, temperature and time showed that temperature had the greatest, although slight, effect on D. eastopi, while saturation deficit, through the host-plant, had a marked effect on D. harrisoni. D. harrisoni populations were dependent on the availability of young leaves. It is concluded that, to avoid attack by Diclidophlebia, transplanting of Triplochiton seedlings should be in late February or early March.