It has been proposed that critical temperatures, desiccation tolerance and the water loss rate have a strict relationship with the microhabitat in which live the spiders. This paper explores the desiccation tolerance and water loss in Loxosceles laeta, a spider causing large percentage of necrotic arachnidism in South America and a potential predator, the spitting spider Scytodes globula, looking for the thermal niche of these species. Specimens of each species were introduced into a chamber with a continuous flow of air through a water absorbent filter, obtaining relative humidity lower than 3%. The daily change in mass, primarily due to water loss was monitored.
