a tool and method for continuous elastomeric band ligation type castration of larger sexually mature animals with an elastic band that must be enlarged by stretching for placement provides an elongate body having a handle at a first rearward end to aid manipulation and an elastic band supporting yoke at a second forward end . the band supporting yoke provides spaced forwardly extending legs for releasable support of the elastic band at two spaced points . band stretching mechanism carried by the body provides an elongate stretching rod that releasably interconnects one course of the elastic band carried by the yoke at a third point between the two yoke support points to stretch the band rearwardly responsive to motion of an associated compound lever mechanism to enlarge the medial orifice defined by the elastic band sufficiently to allow the band to pass over the scrotal pouch and contained testicular structure of a large animal . the elastic band is stretched rearwardly through an annular support carrying a fastening clip that is deformed about the band to maintain tension in the band portion extending about the neck of the animal scrotal pouch . release mechanism disassociates the tool from the elastic band to leave the tensioned band portion about the neck of the animal scrotal pouch at the ligation site .