The venom apparatus, the quantity of venom, and the reactions to the bite of Loxosceles rufescens, L. reclusa, and L. laeta males and females were similar. Both the venom and extracts of whole specimens and of cephalothoraces produced necrotic lesions, erythema, induration, edema, and death when injected subcutaneously into rabbits. Abdominal extracts caused erythema and induration when injected into animals and also hemolysis of human red cells in vitro. The venom exhibited no hemolytic activity.
The venom of the three species gave at least three distinct precipitation lines in immunodiffusion plates. All three components of L. rufescens and L. reclusa appeared to be identical. Immunoelectrophoretic studies of the venom revealed the presence of four antigenic components in all three species. However, the venom from each of these produced a distinctly different pattern.