Friday, May 7, 2010

Here there be (wee) Monsters

Last weekend, while hiking at Cathedral Hills park, I encountered a spider wasp (family Pompilidae) hauling away a large female Trapdoor Spider. At first glance it would seem that a wasp would want nothing to do with a big, fierce spider such as a trapdoor which has a body length of one inch, a leg span of 1 3/4 inches, and outweighs the wasp 4 to1. In fact spider the wasp is the real predators in this matchup. Female spider wasps hunt down spiders, paralyze them with a well placed sting, then haul them to a nest site where they then lay eggs in the victim and bury it. The wasp pupae then emerge to slowly feed on the still-living spider. And you thought you were having a bad day.



If this trapdoor spider reminds you of a small tarantula you wouldn't be far off. They both belong to the same infraorder called Mygalomorphae. This group also includes the very nasty and venomous Funnel Web Spider from Australia. I sent these pics to a spider specialist at Southern Oregon University who confirmed that this was a rather uncommon Trapdoor, but was unable to key to species. Apparently the four species of trapdoor spiders in our area can only be identified to species through the males. Ah well, food for another generation of wasps!



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