by Kate Redmond
Eastern Parson Spider
Howdy, BugFans,
One of the BugLady’s inquilines is an Eastern parson spider. An inquiline (from the Latin inquilinus meaning “lodger” or “tenant”) is an animal that lives in the dwelling of another animal. Like the Tree frog that overwintered with the BugLady last year, the Parson spider is finding enough to eat.
Some definitions of inquiline allow for the possibility that the “roomer” might morph into an eater or an eat-ee of the host, but that would nudge it into a different ecological category. The relationship of the host to its inquiline guest is defined as a “commensal” one – positive for the guest; neutral for the host(ess).
Eastern parson spiders (Herpyllus ecclesiasticus) (great scientific name!) get their name from the white markings on the top of the abdomen that are reminiscent of the white cravats of 19th century preachers. They’re in the ground spider family Gnaphosidae. There are a dozen species in the genus Herpyllus in North America, and most can’t be identified to species with photos. The Western parson spider (H. propinquus – another great name) (the BugLady’s Dad used to introduce juicy vocabulary words when she was a kid, and “propinquity” was one of them, along with “prestidigitation,” “prevarication,” and, of course, “procrastination”) is nearly identical to the Eastern parson spider, mostly separated by range. Eastern parson spiders occur mainly east of the Rockies, from Canada into Mexico.
These small, hairy spiders live on the ground under rocks, logs, and other forest debris, and on tree trunks, but it’s not uncommon for them to get into mailboxes, where they might be collected with the day’s mail, or to come indoors in fall, where adults may overwinter (they don’t breed indoors).
Females are about 3/8” long, and males are about ¼”, and they are speedy spiders that often run in a zigzag line, so the BugLady photographed her spider at the bottom of her “Invertebrate-Catch-and-Release Jar,” a repurposed parmesan cheese shaker. Contributors to bugguide.net have done better – here’s a good shot https://bugguide.net/node/view/1399774/bgimage and a glamour shot https://bugguide.net/node/view/1635888/bgimage.
Eastern parson spiders don’t spin trap webs, they’re active, nocturnal/crepuscular hunters that search for their prey – small invertebrates, including other spiders – on foot. This one has subdued a moth that was bigger than it was https://bugguide.net/node/view/1002561/bgimage. They do use silk for other purposes – they rest in silk retreats under boards, bark, rocks, etc. in the daytime, young spiders that stay outside during winter make a silk cocoon under loose tree bark, and females enclose their eggs in a silken sac in summer before hiding it (and they stay around to protect it). Not a lot is known about their natural history, but the fact that adult parson spiders can be found in any season suggests that they may have a two-year life cycle.
Along with the usual “Scare sites” that pop up when you Google animals (“Eastern parson spider bite”/“Eastern parson spider poisonous”), there’s some discussion about whether the Parson spider’s bite is problematic for humans, beyond the rare individual who might be allergic. The conclusion seems to be that the bite is painful and may produce some temporary inflammation, but it’s not a medical emergency, and the odds are good that you’ll never be bitten by one because spiders would rather flee than fight. As one author points out, spider bites are very rare occurrences and misinformation is rampant.
Kate Redmond, The BugLady
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