September Spider Sleuthing in the San Juans – Day 10 – A Home with Folding Doors


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!

Antrodiaetus pacificus – San Juan Island, WA 08.10.2020
Antrodiaetus pacificus – San Juan Island, WA 08.10.2020
Antrodiaetus pacificus – San Juan Island, WA 08.10.2020

2 comments

  • Glad somebody can love these fellows. Brrr! Not in my bed, please!

    Typo alert: the wasp lays her eggs in the spider, not the spider.

    Greg Bear ventured in an essay that the ichneumon wasp, which has a similar egg-laying habit, informed the conceptualization of the Alien movies.

    Like

  • "BUGGING" YOU FROM FRIDAY HARBOR!

    Thanks Paul! Just made a note to self (me). I need to type these posts up earlier in the day. 😁

    Like

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s