Alpenus investigatorum is a moth of the family Erebidae. It was described by Ferdinand Karsch in 1898. It is found in Ethiopia, Somalia, Kenya, Uganda, Tanzania, Mozambique, Malawi, Angola and Ghana. The larvae feed on Begonia, Carica papaya, Commelina, Aster, Bidens pilosa, Cosmos, Dahlia, Galinsoga parviflora, Zinnia, Ipomoea batatas, Brassica oleracea, Ricinus, Zea mays, Gossypium, Morus, Boerhavia, Arachis hypogaea, Russelia juncea and Nicotiana tabacum.