Castnia licus Drury, in the larvae stage, is a major pest in the sugarcane industry of Northeastern Brazil (giant borer). A natural hemagglutination activity was detected in the larvae hemolymph of this insect and the activity have not been inhibited by tested carbohydrates. Fractionation with ammonium sulfate showed that the supernatant of the 15-30% fraction (S15-30%) had the lectin’s highest specific activity. Acidic and basic lectin activities were separated by chromatography on CM-cellulose; the fractionated molecular forms showed distinct electrophoresis mobilities.