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Bug of the Week is written by "The Bug Guy," Michael J. Raupp, Professor of Entomology at the University of Maryland.

Spiders in corners, Part 1: Common house spider, Parasteatoda tepidariorum


It’s often a topsy- turvy world for common house spiders like this one on the roof of my carport.


Common house spiders have no regrets about dining on members of their own kind. 

One evening last week while I peered out my window at two white-tailed deer destroying shrubs in my backyard, I noticed mortal combat underway in the upper corner of the kitchen window.  A hapless snowy tree cricket was snared in loose strands of a spider web in the upper corner of window frame. The thin tangle web was the handiwork of the common house spider. If you’re a spider, corners of window frames must be excellent locations to build webs as more than one such web adorn windows around my home. At night, light streaming through the window acts as a beacon, luring unsuspecting prey into the sticky threads where they are entangled, paralyzed by the spider’s bite, and pulverized by chelicerae. You can catch some of this pulverization action at the previous episode “Wolves on a summer’s night.”

The common house spider was first described in Germany, but is believed to be South American in origin. It is now found in many lands, likely transported by man as plants and goods moved around the world. In addition to unfortunate tree crickets, Parasteatoda is known to eat small flies, other spiders, cockroaches, and even scorpions. As I watched the spider’s conquest of the cricket I was impressed by the remarkable craft employed by the spider. The first bites of the attack were delivered to the cricket’s long antennae, far away from the crickets potentially damaging legs and regurgitated defensive secretions dripping from the victim’s jaws. As the cricket’s thrashing subsided, bites were delivered to legs and tetanic shaking and complete immobilization soon ensued. On the morning following the attack all that remained of the victim was an empty shell, the bodily fluids of the cricket apparently completely drained. What a way to go.


Despite thrashing legs and regurgitating defensive fluids, the cricket succumbs to venomous bites to the antennae and legs.

The common house spider belongs to a clan called the Theridiidae, spiders that include the black widow, considered by many to be the most dangerous spider in North America. While the bite of the common house spider is not considered dangerous to humans, it was more than sufficient to bring down the cricket many times its size. Common house spiders usually occur in collections of one or two around window frames. However, sometimes prey are uber-abundant and when conditions are right house spiders may become partners in building enormous communal webs, vast killing fields for hapless arthropods. One such mega-web was described at a waste treatment plant in Maryland where vast numbers of prey items, small flies called chironomid midges, were present for extended periods of time. This mega-web occupied tens of thousands of square and cubic feet over a span of 4 acres and likely contained more than one hundred million spiders, of which almost six million were common house spiders. Yikes!    


Bug of the Week thanks Dr. Jeffery Shultz for identifying the spider featured in this episode and Dr. Nancy Breisch for providing inspiration and guidance for spider stories. References used in this episode include “An Immense Concentration of Orb-Weaving Spiders With Communal Webbing in a Man-Made Structural Habitat” by A. Green, J. Coddington, N. Breisch, D. DeRoche, and B. Pagac; and “The Common House Spider, Parasteatoda tepidariorum (C. L. Koch) (Arachnida: Araneae: Theridiidae)” by G. B. Edwards.