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Achaearanea tepidariorum | Agelenopsis aperta | Larinioides cornutus | Physocyclus mexicanus | Hazardous Species

Physocyclus mexicanus

Cellar Spider

Family Pholcidae

3 spiders feeding on waxworm moth

This is a tentative identification by the pholcid expert Bernard Huber, based on a very short description and small drawing in the 1898 description of the species.

 Physocyclus mexicanus is a very hardy, quasi-social pholcid, which we frequently find in packrat dens in central Arizona.

When allow to breed freely in larger spaces they can aggregate into large colonies container hundreds or even thousands of spiders, with number adult females with eggs, juveniles of all stages and numerous attending males.

As seen on Mythbusters

This spider was featured in episode 13 of the Mythbusters program, debunking the myth that daddylongleg spiders are the most venomous but are too small to bite. We were able to show that their venom was not as lethal to mice as black widow venom and that their fangs, albeit very small, are more than long enough to bite into thin skin. We even got one to bite Adam!

Bites and Venom

Like most spiders, these spiders can bite and have venom but the fangs are very small and they only have minute amounts of venom, so the bite is shallow and they symptoms are mild. There may be a stinging sensation and slight inflammation, which do not last for very long.

Curiously, the males have more venom than females, are much more likely to bite than females and almost never bite unless they are disturbed in their webs. We have never seen wandering spiders bite but they can become quite aggressive when groups are disturbed and this aggression can be against other spiders as well as humans. This might suggest that the males are responsible for defending the group, a specialized division of labor that might be unusually in spider social groups but common in insect societies. Soldiers are common in ant and termite societies.

Products

Spider Pharm is currently working with Physcocyclus mexicanus, a species which is common in packrat dens in our area.

Live adult female

Live adult male