It was possible that, if transported to Mr Barrow's garden on pea straw, it arrived with other spiders but would not have laid any of its own eggs because it had not completed its final skin moult, he said.
While redback spiders tended to keep to themselves and not move around much, studies in Japan had shown they could travel long distances, either by walking or by hitching rides under trucks, Dr Vink said.
It seemed likely Mr Barrow's spider had been transported to Albert Town because a vegetable garden was not the most suitable habitat for a redback, which liked dry, rocky locations and twigs.
Alternatively, it could have arrived because there was an established population nearby, he said.
There are several established populations of redbacks in Central Otago, including around the base of Mt Roy near Wanaka, and also around Cromwell and Alexandra.
