Bugging You From San Juan Island

I found this spider in our barn in August and thought it was dead, so I did what I often do – grab it and pick it up! Hmmm. This spider moved. It was alive.

This is a Folding Door Spider, Antrodiaetus pacificus. While I’m not 100% certain, I do believe this is a male since there was no burrow nearby and it’s “wandering” season. Most of the time, females are inside or near the entrance to their burrow.

Folding door spiders are the “tarantulas” of the Pacific Northwest. Their scientific name comes from Greek antrodiaitos (αντροδιαιτος)- “living in caves”, from antron (αντρον)- “cave” + diaita (διαιτα)- “way of life, dwelling” – according to https://bugguide.net/node/view/23442 They build their homes (burrows) in rotting or decaying wood or moss, living in moist, forested areas where they are rarely seen.

Females are approximately 13mm in size, with males a bit smaller at 11mm. They are classified as Mygalomorph spiders, the more primitive spiders with one pair of book lungs.

Occasionally, they become victims of spider hunting wasps. These wasps sting and paralyze the spider, then drag them into a burrow. The wasp lays her eggs on the spider, then leaves. The developing larvae feast on the poor spider while it is still alive.

Please be kind to these harmless, gentle giants!