Ecology ofAcigona ignefusalisHampson, which is an important insect pest of pearl millet in the Sudano-Sahelian zone of West Africa, was studied in Senegal. The pest had two or three generations in a crop season with maximum activity in August–October. Pearl millet and a grass,Pennisetum purpureum Schum., supported a higher population of borers than sorghums. Vertical distribution of borers in the millet plant was influenced by insect feeding site, plant height, stalk thickness, internodes, and stalk condition. Millet stalks and stubble left in the field after harvest and stalks used for housing harbored the diapaused borers during off-seasons. Partial burning of infested green stalks proved to be effective and practical in checking carry-over of the pest.