The armyworm (CLA) causes major damage to cereal crops, particularly maize. In the Democratic Republic of Congo, recent data indicates that the regions currently most affected are Sud-Ubangi, Nord-Ubangi, Lualaba, Kasaï Central, Haut-Katanga and the Kivus. In this study, the level of CLA infestation was assessed as a function of altitude and cropping associations in Nyiragongo Territory. Observations were made in 10 fields, taking altitude into account. The results indicate significant variations in incidence and severity as a function of altitude (p = 0.01), but not in the equivalent density coefficient (p > 0.05). Thus, it appears that increasing altitude plays a crucial role in reducing the spatial distribution and spread of the armyworm. It should be stressed that other factors, such as variations in the availability of host species and natural enemies, can also have a significant influence on the level of infestation. The role of crop association in reducing CLA population density is also discussed.