We tested the hypothesis that the response of Paraphidippus aurantius (Lucas 1833) (Salticidae) to a simulated threat of predation would depend on a combination of spider size and reproductive status. In ponderosa pine forests of Colorado we located nests with spiders of varying sizes that were either adult female spiders guarding offspring or juvenile female and male spiders. To simulate a predator threat we applied a disturbance to the sides of spider nests using repeated puffs of air expressed from a rubber bulb or by blowing. We recorded the threat intensity (number of puffs) required to displace spiders from their nests, and then monitored the immediate responses of spiders to this threat. The threat intensity required to displace spiders guarding offspring was 2.3 times that of non-guarding spiders, and guarding spiders fled less than half as far as non-guarding spiders. Spider size had no effect on the threat intensity required for displacement, but larger spiders fled further than small ones. We then destroyed nests and monitored the long term responses of the spiders. Nests containing offspring were constructed with 4.6 times the mass of silk as those without offspring. When spiders rebuilt their nests, spider tenure in rebuilt nests did not differ between guarding spiders and non-guarding spiders. Spider size was negatively related to nest tenure for non-guarding spiders, but there was no such relationship for guarding spiders. These results suggest that both the short term and long term outcomes of interactions between P. aurantius and other predators may be influenced by a combination of spider size and offspring guarding behavior.