Preliminary studies in rabbits demonstrate that envenomation by the male Tegenaria agrestis spider produces a slowly developing dermal lesion, which exhibits gravitational drift and extensive subcutaneous hemorrhaging. Petechial hemorrhages were present on the lungs, liver and kidneys of rabbits bitten by male Tegenaria agrestis. Female Tegenaria agrestis trials in rabbits produced no significant effects in New Zealand white rabbits, but produced dermal lesions in the California giant strain.