OBJECTIVE: Screening and biochemical characterisation of trypanosome-lysing factor (trypanolysin) from non-vector insect, Schistocerca gregaria. DESIGN: Laboratory based experiment. SETTING: Department of Biochemistry, University of Nairobi. RESULTS: Lysis of isolated trypanosomes was demonstrated with midgut homogenates of natural vector Glossina morsitans centralis as well in non-vector insects. The highest trypanolytic activity was observed in midgut homogenate of the desert locust. Schistocerca gregaria followed by the cockroach, Periplaneta americana (L). Further studies on the S. gregaria trypanolytic factor showed its proteinaceous nature due to its sensitivity to temperatures above 40 degrees C and to proteases. Additionally, the factor showed lectin-like properties since the activity was blocked by D-glucosamine. CONCLUSION: The trypanolytic factor has the potential of being used to modulate tsetse fly vectorial capacity.