Southern House Spiders Find Spaces That Are Just Right Inside Human Homes
Posted on March 27, 2015
The southern house spider (Kukulcania hibernales) gets its common name due to its preference for residing in human homes. The spiders live in human homes because they can easily find spaces that are "just right" for them. These spaces provide protection from enemies and the weather as well as opportunities to feed. A female southern house spider is pictured above.
A new study from the University of Missouri examined how the house spiders make size-related choices about holes and cavities to build their nests in. The southern house spider builds a nest that radiates outward from a central lair. Pre-existing holes and crevices in human homes make good places for these lairs.
MU biologist James E. Carrel is the author of the study published here in the Florida Entomologist Journal. He says, "We normally think of spiders as living on silken webs or hiding in leaves or under things. But southern house spiders seem to be found only in little holes and crevices up on walls and ceilings and associated with human dwellings."
Carrel theorized that spiders were looking for holes and crevices that more-or-less matched their body size, similar to how hermit crabs trade up for bigger shells. He tested his theory by presenting different sized spiders with multiple artificial holes to nest in. He recorded the hole size each spider chose and measured the growth patterns of the spiders.
Carrel found that little spiders selected little holes for nests and bigger sized spiders chose larger holes. The ratio of the diameter of the nest hole and the size of the spider was constant across the three different age groups tested.
Carrel also says, "Spiders tended to choose a hole that was three to four times as big as their own body size, which is big enough for them to get up, move around, go back, hide, and all." He says that like Goldilocks in the fairy tale the spiders selected a hole that fit "just right." Carrel also says his findings raise the question of whether populations of K. hibernalis in the wild are constrained by the limited availability of suitably sized nest sites.