Abundance of termites, damage to plants and loss in yield were studied on recently-cultivated and long-cultivated fields at Mokwa in the southern Guinea savannah zone of Nigeria. Virtually all damage was caused byMicrotermeswhich have deep, diffuse subterranean nests and attack maize by entering the roots or prop-roots and may eventually extend their foraging by excavating the stem to heights varying from a few centimetres to over a metre. Attack on the roots commences at 10 to 12 weeks after planting and intensifies as the plants mature. Attacked plants may remain standing or fall over (lodged). Yield of grain on standing attacked plants was not significantly different from yield on standing unattacked plants. Cobs of lodged plants were damaged on the ground by termites, ants, rodents and pathogens and yield of grain was significantly lower than on standing plants. Yield losses on recently-cultivated fields (1–3 years) varied from 0.1 to 3.0% and on long-cultivated fields (10–27 years) from 3.9 to 9.5%. Abundance ofMicrotermesincreased from 877/m2in the first year of cultivation to 2997/m2after 3 years; on the long-cultivated plots abundance was approximately 4000/m2. Damage (% lodging) and loss in yield were linearly correlated with abundance ofMicrotermesand years of cultivation.