100 Species #16: Fourlined fringetail

A fourlined fringetail (Species #16 Ctenolepisma lineata) briefly pauses its mad dash across the bathroom tile.

The insect order Thysanura* (which means "fringe-tail," referring to the two long cerci** and middle abdominal segment making a three part "tail" of sorts) includes the famous silverfish and somewhat less well-known firebrat. The family also includes this species, which is apparently native to southern Europe, but found along the east coast of North America as well as in California. It may go without saying that it is almost always found indoors, and humans are the cause for it being found so very far from its original range.

Creatures in this order are spectacularly omnivorous, feeding on substances such as bookbinding glue and wallpaper paste. The fourlined fringetail is among a very small number of animals that can digest cellulose (cows and termites cheat by having guts packed with cellulose-digesting microorganisms).

This is the first appearance of this species on this blog! The related species that is actually silver (owing to covering of slippery scales) was 365 Urban Species #275.

* It appears that more up-to-date writers use the name Zygentoma for the order.

** Cerci are also the "pincers" at the back of an earwig, and the sensory tails at the back of a cockroach.

I leaped to this brash identification with the help of these websites:
The indispensable bugguide.net.
UC Riverside's website on Urban Entomology.
I made up the common name.

100 Species #17: Northern Wolf Spider

A Northern Wolf Spider Alopecosa aculeata refuses to hold still for long on my hand.

My step daughter turned this spider up while doing some yard work. She asked why it was called a wolf spider and I explained that it was its mournful howl during nights illuminated by the full moon, and that it hunts in packs and has a rigid family social structure. Actually none of that is true; I didn't even tell her that, but maybe I will next time she asks. Wolf spiders were probably named that back when wolves were hated pests that preyed on livestock, not honorable keystone species found on t shirts in stores that smell like incense. Wolf spiders hunt alone, like most other spiders, and do so without spinning a web. They chase down their prey, which is probably the wolfiest thing about them.


I made my identification mostly from this photo, which shows the orientation of the eyes (crucial when identifying spider) and some other details. If I am right (and I surely could be wrong--identifying spiders to species mostly involves looking at spider genitals under microscopes) then this is a species found throughout the northern hemisphere. The scientific name translates more or less to "Fox spider." I suppose that might be more apt: foxes usually hunt alone, and pounce on their prey. I'd want a "fox spider" to be reddish orange, though. This is a new species to this blog! Previously I have featured other wolf spiders as a "more urban species" entry, and as a curiosity found at Cutler Park (in Dedham before we lived in Dedham!)