Spelungula cavernicola, New Zealand's largest and only protected native spider, was studied for one year in caves in the Honeycomb Hill System, Oparara Valley, near Karamea, South Island. These spiders were found mainly in complete darkness within 10 or 20 m of a cave entrance, but were also present deep in the caves. The numbers of spiders recorded through the year showed little temporal variation except when juveniles emerged from egg sacs. Some short-term variation in numbers may be due to migration in and out of sites, or variable search effort, or both. Spiderling emergence from egg sacs may be seasonal,. but size class data suggest that the timing. of emergence differed between years. The hypothesis that Spelungula lives only one year_ was refuted using size-class data. All size-classes of animals were present all year, and except for newly emerged spiderlings, occurred in uniform proportions, giving evidence of overlap of generations. Two estimates of longevity from size-class data are 3 years and 5 years, which may be underestimates because adult longevity could not be estimated. A preliminary investigation of habitat selection of Spelungula was made using multiple logistic regression of 84 random cave sites. Presence of cave wetas was a significant variable, whereas, passage size, light, water, temperature, humidity, presence of other animals, and distance to cave entrance were not. The implications of these results for conservation management are discussed.