Incubation of fluorescein- and biotin-lectin conjugates with the salivary glands of Glossina spp has revealed inter- and intraspecific variation in the surface carbohydrates of the glands. The degree of Con A binding to the basal laminae of the glands of the two Glossina palpalis subspecies, G.p. palpalis and G.p. gambiensis was markedly different. The infectivity of T.b. gambiense sensu lato isolates to G.p. palpalis and G.p. gambiensis was compared. G.p. gambiensis from the field and from laboratory colonies transmitted T.b. gambiense sensu lato isolated from patients in Ivory Coast whereas G.p. palpalis appears totally refractory to all T.b. gambiense isolates used. Although the relationship between the surface of the basal laminae of the salivary gland exposed to the haemocoele and trypanosome infection is not known the consistent differences observed in lectin binding to the salivary glands suggest that differences in basic physiology of the glands exist which might correlate with susceptibility to trypanosome infection.