Studies on damage by larvae of Eldana saccharina Walker, Chilo zacconius Bleszynski and Sesamia spp. to sugar-cane stands revealed a high degree of correlation between internode damage and stalk damage as well as between internode damage and sugar content of the canes. For every 1% increase in stalk damage there was a corresponding increase of 0.214% in the internode damage. The distribution of larvae inside the internodes was found to depend on the level of infestation. At low field infestation level (below 25 larvae per 100 canes) the distribution was random. As the level of infestation increases, the distribution becomes more aggregated. The distribution of damage in the sugar-cane field was found to depend on the overall stalk damage. The distribution tends to be more contagious when field level of stalk damage was less than 45%. The damage became evenly distributed when stalk damage rose above 60%. An estimation of average loss of sugar caused by stem-borers to the variety NCO 376 (at the field damage rate of 8.6, 10.6 and 3.1% damage for bottom, middle and top parts respectively of the cane) was U.S.S332.10 per ha of field.Resume-Une etude des extraits de travaux sur le degat cause par des larves d' Eldana saccharina Walker, Chilo zacconius Bleszynski et Sesamia spp. aux plantes de canne a Sucre a revele un degre eleve de correlation entre d' une part le dommage a l'entre-noeud et celui du trognon, et d'autre part le dommage a l'entre-noeud et le contenu sucrier des Cannes. A chaque augementation d'un pourcent de dommage au trognon, correspondait une augmentation de 0,214% de dommage a l'entrenoeud. Il's est revele que la repartition des larves au long des entre-noeuds dependait du niveau d' infestation de ceux-ci. Lorsque le nivesu d' infestation du champ est bas (e'est-a-dire au-dessous de 25 larves sur 100 Cannes) la repartition des larves n'est pas reguliere. Par contre, lorsque le niveau d' infestation s' accroit, la repartition des larves devient plus agregee. On constate que l'ampleur du degat dans le champ de canne a sucre depend de 1' ensemble des dommages causes aux trognons. La repartition se revele plus contagieuse lorsque le taux du degat est inferieur a 45%. Lorsque le degat aux trognons atteignait plus de 60%
