Pardosa milvina is a small wolf spider commonly associated with agricultural ecosystems. P. milvina produces dragline silk that is attached to the substrate over which it moves, but is not used in capturing prey. The effect relative humidity on P. milvina behavior and biology was examined through a series of experiments. The water balance constraints of P. milvina were studied to determine its body water content and its water loss rate at 0% RH. The calculated water loss rate is comparable to that of other terrestrial arthropods, and body water content was similar to other Pardosa spp. To examine the degree to which prey items are utilized as a water source, a study was conducted to determine if dehydrated spiders were more likely to take prey than hydrated spiders of comparable satiation levels. The individuals tested did not show an increase in prey taking when under water stress, as no spiders in either treatment took prey. Although they did not take prey, the dehydrated spiders regained a significantly greater mass when presented with water, indicating that free-standing water sources are preferred over prey if the spider is not hungry.
The effect of relative humidity on silk deposition was examined, which necessitated the development of a technique for visualizing the silk. A difference in silk production between spiders maintained at different relative humidity levels was not found. Although there was no difference between relative humidity treatments, an analysis of a subset of individuals by mating status did reveal a difference in silk deposition between mated and virgin females. Virgin females deposited significantly more silk than mated spiders.