Book Review: Dr. Eleanor's Book of Common Spiders

One resource that has been missing from the recent explosion of spider-related material coming from various publishers has been a book aimed squarely at the average homeowner or gardener with something other than an all-consuming passion for arachnids. "Dr. Eleanor" to the rescue with Dr. Eleanor's Book of Common Spiders (Chicago: The University of Chicago Press. 2018. 96 pp.).

Eleanor Spicer Rice, who already has several related titles under her belt, mostly about ants, has teamed up with Chris Buddle to deliver a nicely organized, thoroughly researched book on the spider species that the public most often asks about. You know, the eight-legged critter crawling across the kitchen floor, the infamous "shower spider," and the ones you always see in the (insert shed, basement, garage, or other appropriate venue).

The authors treat their subjects with accuracy, clarity, and brevity, while still managing to cultivate the same sense of fascination in the reader that they, as scientists and writers, have already found for themselves. This is no small feat. There is a dash of humor here and there as well, and they are not above poking fun at themselves. Color photographs, mostly by Sean McCann, complement the lively text and enhance the impact of the book. Whether arachnophobes will reach for it on the bookstore shelf, or over the online vendors remains to be seen. I hope they do.

Even if the book were a complete failure otherwise, it would bear recommending for this passage alone:

"Striped lynx spiders prefer biding their time in agricultural fields. When we plant our crops with only one or two types of plant per field, we humans essentially sow arthropod grocery superstores. In nature, any given species of plant is often mixed in with other plant species and so bugs that like a particular plant species may need to search to find the plansts they like. As a result, only a limited number of bugs can live in an area. It's like living in a town with a gas station-sized grocery store. In our human-planted superstores, however, tons of insects that like our crops can move into the giant all-you-can-eat buffet of a farm, filled with only their favorite foods. These insects become agricultural pests, gobbling up billions of dollars' worth of food we grow for ourselves each year."

Exactly. I have said the same thing myself in my own publications, about how humans are responsible for creating their own insect pests. Further, all the crop plants are equally vulnerable because they have identical genetics. Not so in nature. Watch a butterfly laying eggs. She won't oviposit on every plant; only on those a little weaker in their chemical defenses.

My only quibbles with the book stem mostly from the fact that I am a writer, too. There were a couple of bad word choices, but I see worse errors in other books. There was one implied assertion that is incorrect, however. In the Frequently Asked Questions part of the back matter, one FAQ concerns whether all spiders are venomous. The authors indicate they are. This is not true. Spiders in the family Uloboridae, common in North America, lack venom glands. Lastly, there are some common English names for certain spider species or genera that were apparently created just for this book. There is no such thing as a "Ceiling Spider," even though I would endorse that name for Cheiracanthium species because that is exactly where you encounter them.

Enough nit-picking. The "up sides" of this handy volume are much more numerous. It is a paperback, and of a size that is large enough to not lose easily in a stack of other books, and comfortable to handle for those of us who are all thumbs. Again, the text is a joy to read. Spicer and Buddle manage to give each spider a personality that reflects its biology. This style comes close to anthropomorphism, but I am all in favor of whatever it takes to win more arachnophiles. Spiders need all the friends they can get in Humanland.

One of my measures of the goodness of a book like this is whether it teaches me, a longtime naturalist, something new. This book did that, in spades. I love being surprised with new knowledge, and with that I heartily recommend Dr. Eleanor's Book of Common Spiders.

"Arach" is Back!

One of the things I look forward to each autumn is the annual Flickr event known as "Arachtober". It is a Flickr group which slumbers between November and the following September, but remains a tradition among arachnophiles and macro photographers. There are always mesmerizing images posted from all corners of the globe.

Marbled Orbweaver, Kansas

Arachtober manages to recruit several new participants each year through word of mouth, blogs, and sheer curiosity. Not only spiders, but scorpions, ticks, mites, harvestmen, and all other arachnids are eligible for inclusion. Don't forget the artistry of spider webs, too, whether dew-adorned or dry.

Apache Jumping Spider male, Colorado

The only hard and fast rule of Arachtober is that the images you post to the group must not have appeared on your own Flickr photostream previously. Allowed quantity of images per day varies at the discretion of the group administrator.

Banded Garden Spider female, Colorado

Overall, interest in spiders seems to be increasing among the general public, and arachnids are achieving a much higher profile than ever before. This is great news, for there is still a great deal of work to be done to combat myth, superstition, misinformation, and fear.

Wolf spider, Alopecosa sp., Colorado

Please consider contributing to "Arachtober" on Flickr, or find another way to dedicate some time to sharing your spider observations, questions, or images. There are many groups on Facebook devoted to spiders and their identification, for example; and presumably, the same applies to Instagram. There is much you can contribute to our collective knowledge by doing so. Thank you.

Jumping Spider, Phidippus insignarius

While exploring Cheyenne Mountain State Park on June 3, I caught glimpse of a very colorful jumping spider prowling a dead thistle stalk among some branches of scrub oak (Gambel's Oak). My first thought was it must be a male Phidippus of some kind, but I am used to them being a fair bit larger than this one was. Well, I was excited to find out later that it was indeed a male Phidippus insignarius.

The crazy thing is, I was already familiar with that species, thanks to some simply stunning images by Patrick Zephyr and Raed Ammari. I only remembered these head-on pictures, and forgot what the whole spider looked like.

I had also forgotten, or never knew, that P. insignarius is found here in Colorado. Indeed, it ranges from here east through Nebraska, Iowa, Kansas, eastern Oklahoma, Missouri, southeast Minnesota, Illinois, Indiana, Kentucky, Tennessee, Pennsylvania, southern New England, New Jersey, Virginia, and North Carolina. Look for it in the understory of open woodlands and prairies. The oak thicket with scattered pines in an otherwise grassland habitat where I found this one seems to be the ideal habitat.

P. insignarius is not a terribly large spider. Mature males average just under 5 millimeters in body length, females 5.45 millimeters. The coloration of the female, from all I can gather, is similar to the male, but without the bright white hairs on the carapace, legs, and palps. Both genders have the bushy "eyebrows" that are characteristic of many Phidippus species.

If you are all ready to go searching for jumping spiders now, consider investing in a "beating sheet," or make your own. A friend of my wife who is an accomplished seamstress, whipped one out for me in no time. We chose a heavy, durable canvas (still prone to deformation with a good stiff breeze), about two feet square. Triangular pockets in each corner receive wooden slats arranged in an "x" pattern with a screw in the center to join them.

Beating sheet in use ©knoxnews.com

The beating sheet is held under the branch of a tree or shrub, and a heavy stick or rod is used to sharply strike the branch. All manner of spiders, and insects, of course, can come raining onto the sheet. This is the best way to collect many cryptic arthropods that are seldom seen otherwise.

Sources: Edwards, G.B. 2004. "Revision of the Jumping Spiders of the Genus Phidippus (Araneae: Salticidae)," Occasional Papers of the Florida State Collection of Arthropods. Volume 11. 156 pp.
Hollenbeck, Jeff. 2007. "Species Phidippus insignarius," Bugguide.net

Aculepeira Orb Weavers

It takes little to excite me when I am out in the field, but back on July 13 I happened upon a spider that was new to me. My wife and I were hiking in Lovell Gulch, just outside of Woodland Park in Teller County, Colorado, enjoying the mixed conifer and aspen forests at an elevation of roughly 8,500 feet. I seem to recall watching an insect in flight when an orb weaver spider caught my attention.

The underside of the spider was most visible as it sat in the hub (center) of its wheel-like web, so I maneuvered as best I could to get a dorsal (top side) view. My initial thought was that this was a spider I had seen dozens of times: the Western Spotted Orb Weaver, Neoscona oaxacensis. Still, something seemed a little bit "off," and sure enough the ventral markings on this spider's abdomen were very different from that of a Neoscona species.

Underside of A. packardi

Underside of Neoscona oaxacensis

Once I got back home, I tried my hunch that it might instead be a species of Aculepeira, even though I had never seen a specimen before. Indeed it was. It turns out that this genus is pretty much restricted to high elevation, and/or high latitude habitats. The three North American species are collectively found from Alaska and the Yukon Territory to northern Mexico. There are also a few records in the northeast U.S. One undescribed "prairie species" has been discovered in western Washington state.

This one is almost certainly Aculepeira packardi, but it takes a microscopic examination of the genitalia of adult specimens to be conclusive. Note that the species name in older references is spelled with two "i"s: A. packardii. The other two species here are A. carbonarioides and A. aculifera (which reaches Guatemala).

Normally, the adult female spider hides in a silken retreat on the periphery of her web during the day, but this was a mostly cool, overcast day, so she may have felt comfortable occupying the center of her snare. The web was strung between the branches of a very low-growing shrub on a gentle slope in an open meadow.

These are good-sized spiders, mature females averaging nearly 11 millimeters in body length, males about 6 millimeters. The markings are pretty consistent, too, which does help a little bit in determining the species.

Interestingly, A. packardi also ranges in the Russian far east, Siberia, and northern China. In North America, it ranges from the Yukon to Labrador, and south to Chihuahua, Mexico and Pensylvania.

One typical dorsal pattern of Neoscona oaxacensis

From now on I will always double check spiders that I "think" I already know. It is a good practice, for you never know if you will find something new; new to you, or even new to science. All text and images © Eric R. Eaton

Sources: Balaban, John and Jane, et al. 2015. "Species Aculepeira packardii," Bugguide.net.
Dondale, Charles D., James H. Redner, Pierre Paquin, and Herbert W. Levi. 2003. The Orb-weaving Spiders of Canada and Alaska (Araneae: Uloboridae, Tetragnathidae, Araneidae, Theridiosomatidae), The Insects and Arachnids of Canada Part 23. Ottawa, Ontario: NRC Research Press. 371 pp.
Schimming, Lynette. 2013. "Genus Aculepeira," Bugguide.net.

Thin-legged Wolf Spiders, genus Pardosa

Most people think of wolf spiders as big, hairy monsters just this side of a tarantula in size. A few species are, but the overwhelming majority are mid-size or even downright "compact." Case in point, the most overwhelmingly abundant wolf spiders you are likely to encounter are in the genus Pardosa, the "thin-legged wolf spiders." They are mostly small and medium-sized.

Male Pardosa on a streamside rock, Arizona

Wolf spiders in general are rather easily identified by their eye arrangement. Four small eyes are in the front row, lowermost on the face: the anterior medians (center pair), and anterior laterals (one on each side of the anterior medians). The next row is composed of two enormous eyes, the posterior medians. Last in line is one pair of posterior laterals, usually well back on the carapace from the other sets of eyes.

An example of a woodland Pardosa species, male, Colorado

How does one identify Pardosa in particular? Look at the legs. Pardosa has long spines that are almost perpendicular to the axis of the leg itself. Most all other wolf spiders have shorter spines that are more nearly parallel to the surface of the leg. The hind pair of legs is long, and it is often easier to see the spines on that rear pair.

Very dark Pardosa male from high elevation in Colorado

Thin-legged wolf spiders often exhibit some degree of sexual dimorphism, too. Mature males may have a completely different color pattern from females. Identification of species hinges on microscopic examination of the genitalia. Females have a paired genital opening called an epigynum. Males have highly modified pedipalps they use to deposit sperm into the epigynum, like a key fitting in a lock. The pedipalps of a mature male spider resemble little boxing gloves near his face.

Female Pardosa with egg sac attached to her spinnerets

There are sixty-five (65) species of Pardosa currently recognized in the U.S., and 75 species north of Mexico if you include Canada. They collectively measure 3 to 12 mm or so in body length as adults. The cephalothorax is higher than in most other wolf spiders, and the sides of the face are nearly vertical.

Many wetland Pardosa species resemble this one in Colorado

Thin-legged wolf spiders are perhaps most abundant around water, be it a rocky streambed, or marshy wetland, or beach around a lake. They can also be found in wooded areas, prowling the forest floor, scrambling over logs, or darting among leaf litter. Fields are full of them, too, even the edges of agricultural plots. They also occupy some of the highest elevations of any North American spiders, so look for them in the mountains, too. It is interesting that some species can be found in several different habitats, whereas most spiders are confined to one or two (as are several Pardosa species). In short, it is difficult to not find these spiders.

Another Pardosa on a rock in Arizona

Sources: Bradley, Richard A. 2013. Common Spiders of North America. Berkeley: University of California Press. 271 pp.
Vogel, Beatrice R. 2004. "A Review of the Spider Genera Pardosa and Acantholycosa (Araneae, Lycosidae) of the 48 Contiguous United States," J. Arachnol. 32: 55-108.

Dimorphic Jumping Spider, Maevia inclemens

When I lived in Ohio I had the great honor of being introduced to Dr. George Uetz at the University of Cincinnati. At the time he had a graduate student, Dave Clark, who was doing research on the courtship behavior of the Dimorphic Jumping Spider, Maevia inclemens. Ever since then I have had a special place in my heart for this unique member of the Salticidae.

"Tufted form" male, Missouri

What makes this spider so special, you ask? The name says it all. The male of this species comes in two distinct forms: a "tufted form" that is all-black with white legs; and a "gray form" with black pinstripes and orange spots and chevrons. Not only do they look like separate species, but they behave like two different spiders, too. Each male performs a complex dance that is different from that of the other form.

"Tufted form" male, Indiana

The tufted form, named for the triple-Mohawk style hairdo, literally stands on tiptoe, dips his abdomen, and waves his front pair of legs overhead at a prospective mate. The gray form takes a "low rider" position and sidles back and forth.

"Gray form" male, Kansas

Dave Clark capitalized on those differences, as well as his expertise in video, and created animations of a tufted form male doing a gray form dance, and vice versa. He then played his mixed-up dance mix in front of live female spiders. Jumping spiders have better eyesight than any other terrestrial invertebrate, so they could actually watch, and react to, the videos on a monitor. This was back in the late 1980s, so Dave dubbed his lab "MTV" for "Maevia Television."

"Gray form" male, Kansas

The Dimorphic Jumper is a species commonly encountered in the eastern half of the U.S. where it prowls understory foliage, climbs on walls and fences, and occasionally enters homes. These are not overly large spiders, males ranging from 4.8-7.0 millimeters in body length, females 6.5-10 millimeters. Females have consistent markings, being mostly pale with a pair of orange or red racing stripes running down the back of the abdomen.

The first time I saw a tufted form male of this species, it was on a sidewalk in Cincinnati and I initially mistook it for a carpenter ant. This species is not generally considered an ant mimic, but considering that carpenter ants forage in the same places as Maevia, it is not out of the question I suppose.

Juvenile female or gray form male, Massachusetts

So what was the result of those experiments? The dance of the black form male is apparently more successful at attracting the attention of a female from a greater distance, while the dance of the gray form male is better at wooing a lady spider closer to him. You can see videos here on YouTube of both kinds of males performing. There is no word on whether the females presented with the wrong combo of male appearance and dance moves suffered psychological damage.

"Is there a female down there?"

Sources: Bradley, Richard A. 2013. Common Spiders of North America. Berkeley: University of California Press. 271 pp.
Clark, David L. and George W. Uetz. 1993. "Signal efficacy and the evolution of male dimorphism in the jumping spider, Maevia inclemens," Proc. Natl. Acad. Sci. USA 90: 11954-11957.
Guarisco, Hank, Bruce Cutler, and Kenneth E. Kinman. 2001. "Checklist of Kansas Jumping Spiders [illustrated]," Kansas School Naturalist 47(1).
Moffett, Mark W. 1991. "All Eyes on Jumping Spiders," Nat. Geo. Mag. 180(3): 42-63.

Two-spotted Cobweb Weaver and kin

Colorado Springs is blessed with a number of concrete bike trails throughout the city, including parks like Garden of the Gods. At this time of year, one can find numerous insects, spiders, and other arthropods parading across these paths. One example I encountered the other day was a male of the Two-spotted Cobweb Weaver, Asagena americana.

Male Asagena americana, Garden of the Gods

This arachnid could easily be mistaken for some kind of ground-dwelling spider instead of a web-spinning one. Males are only 3.2-4.4 millimeters in body length, but they are stout, with short, muscular legs. The underside of the femur of each leg is studded with short teeth and/or spurs. Females are much more delicate in appearance by comparison, but only slightly larger (3.5-4.7 mm).

While most male spiders go wandering in autumn, this is one of those species found most commonly in spring. Males have been collected from May through July, females May through August. The species ranges across most of North America.

Being conspicuous has its price. Male and female Asagena americana are frequent victims of Black and Yellow Mud Dauber wasps that sting them into paralysis and stuff them in a mud cell as food for the wasp's larval offspring.

Another interesting feature of the male is his "singing" mechanism. The rear of the carapace bears a "stridulating organ" on each side of the pedicel (the narrow connection between cephalothorax and abdomen). The front edge of the abdomen has a semicircular hardened plate that apparently rubs against the stridulating organs to create sound.

Female Two-spotted Cobweb Weavers can be found in their webs under stones, among leaf litter, under bark on decaying logs, and in moss. Mated females produce spherical, translucent egg sacs 4-5 millimeters in diameter containing 20-30 pale yellow eggs.

Asagena fulva from Tucson, Arizona

A related species, Asagena fulva, is common in the southwest U.S., north to Oregon and east to Florida. It is slightly larger, females ranging from 3-5.9 mm, males 2.4-5 mm. They appear "redder," with more white markings than their two-spotted cousins. I found them commonly under stones, garbage barrels, and other cover in the Sonoran Desert of Tucson, Arizona. This species might be an ant specialist, as entomologists have found them camped out in webs at the edge of harvester ant nests, presumably ambushing worker ants as they leave, or return to, the nest.

Both of these species were formerly classified in the genus Steatoda, several species of which are frequently mistaken for black widows.

Asagena fulva from Tucson, Arizona

Sources: Bradley, Richard A. 2013. Common Spiders of North America. Berkeley: University of California Press. 271 pp.
Fitch, Henry S. 1963. Spiders of the University of Kansas Natural History Reservation and Rockefeller Experimental Tract. Lawrence: University of Kansas Museum of Natural History. Miscellaneous Publication No. 33, pp. 1-202.
Levi, Herbert W. 1957. "The Spider Genera Crustulina and Steatoda in North America, Central America, and the West Indies (Araneae, Theridiidae)," Bull. Mus. Compar. Zool. 117(3): 367-424.

Bridge Orbweaver (Gray Cross Spider)

Downtown Portland, Oregon features a promenade on both sides of the Willamette River, and it is a stroll, bike ride, or jog worth taking simply for the scenery and people-watching. Should you be interested in spiders, it is even more worthwhile. Many manmade structures are occupied on the exterior by the Bridge Orbweaver, Larinioides sericatus. Even in December and early January of this year, specimens of varying ages were abundant.

This species is also known as the "Gray Cross Spider," and it is easily confused with the very similar Larinoides patagiatus, which has no common name. Further complicating matters, the Bridge Orbweaver has been going by the Latin name L. sclopetarius until very recently. A revision of the genus Larinioides was published in the journal Zootaxa about two months ago (see citation below).

These are fairly large spiders, mature females measuring 8-14 millimeters in body length, and males 6-8 millimeters. Their legspan makes them appear even larger to the untrained eye. Both genders share the same distinctive pattern on the carapace (top of cephalothorax) and abdomen. The overall color is generally gray, but some specimens tend toward brown.

Mature male from Massachusetts

The spider normally hides in a retreat on the periphery of its circular web during the day, and emerges to repair or reconstruct the snare at night. The spider then spends the night in the hub of the web, hanging head down. The spiders can also be there in the center of the web on overcast days, and juvenile specimens tend to be more likely to occupy the hub during the day than mature individuals.

Female making a kill in Massachusetts

While this species is particularly common close to water, where emerging aquatic insects like midges and mayflies are an abundant food source, I have also seen the Bridge Orbweaver in other settings in western Massachusetts. It can be a fixture around outdoor lights, where insect prey is drawn in great numbers. Spiders are quick to take advantage of resources like that, and competition for prime "web sites" is keen.

Underside of adult female, Oregon

Larinioides sericatus is found not only in the U.S. and Canada, but Europe as well. It is strongly suspected that it was even introduced to North America from the Old World. Records from Asia are now attributed to yet another species, L. jalimovi. Here, the Bridge Orbweaver is known from the maritime provinces, Quebec, Ontario, Alberta, and British Columbia south to Minnesota, Wisconsin, Illinois, Indiana, Ohio, New England, Virginia, Kentucky, Washington, and northwest Oregon. Isolated records exist for extreme northeast North Carolina, Oklahoma, and northwest Utah, at least some of which probably need confirmation. Recent voucher specimens have been taken in Long Beach, California.

Special thanks to Ivan Magalhäes and Laura Lee Paxson on the Facebook page for the American Arachnological Society for setting me straight as to the proper scientific name for this species.

Sources: Bradley, Richard A. 2013. Common Spiders of North America. Berkeley: University of California Press. 271 pp.
Dondale, C. D., Redner, J. H., Paquin, P. & Levi, H. W. (2003). The insects and arachnids of Canada. Part 23. The orb-weaving spiders of Canada and Alaska (Araneae: Uloboridae, Tetragnathidae, Araneidae, Theridiosomatidae). NRC Research Press, Ottawa, 371 pp.
Hollenbeck, Jeff, et al. 2013. "Species Larinioides sclopetarius - Gray Cross Spider," Bugguide.net.
Šestáková, Anna, Yuri M. Marusik, and Mikhail M. Omelko. 2014. "A revision of the Holarctic genus Larinioides Caporiacco, 1934 (Araneae: Araneidae)," Zootaxa 3894(1): 061-082.

Missing Sector Orbweaver, Zygiella x-notata

During my stay in Oregon during December and the first week of January, I was surprised to see how many spiders were still active in the relative cold and damp. The most conspicuous of those arachnids were the Missing Sector Orbweavers, Zygiella x-notata, which seemed to occupy the corner of every window frame, outdoor light, or other manmade structure.

This species is easy to identify, simply from the web alone. It looks as if the spider forgot to finish it. A substantial wedge of the sticky spiral is missing from the top half of the web, the central radius in the sector running to a tubular retreat on the periphery where the spider usually resides. The web spans anywhere between 6-14 centimeters in diameter.

Zygiella web, spider in upper right corner

The spiders will come out to sit in the hub (center) of the snare at night, or even on overcast days; and young spiders are more apt to station themselves at the center than older spiders. Adult females measure 7.4-8.7 millimeters in body length, males 6-6.5 millimeters. The color and pattern is pretty consistent across all specimens, as shown in the images here.

Male specimen

Zygiella x-notata is not native to North America, having been introduced here from Europe who knows how long ago. It is well-established here now, from the California coast through western Oregon and Washington, and also along the Atlantic coast, from New England to Virginia. Another adventive species, Z. atrica, is known from northwestern Washington and southern British Columbia. Z. nearctica is boreal, occurring coast to coast in Canada, plus Alaska, New England, the Rocky Mountains to Colorado, and the Appalachians to North Carolina.

Two native species formerly placed in Zygiella have been reclassified into the genus Parazygiella: P. carpenteri with a disjunct occurrence in the Sierra Nevada mountains, California coast, and also southeastern Washington; and P. dispar from southern British Columbia to the vicinity of Monterey, California (though this is a holarctic species also found in Europe). P. carpenteri usually spins a complete orb web.

Spider in tubular retreat with egg sac

Back to Z. x-notata. It is also known under the aliases of "Winter Spider," "Opensector Orbweaver," and "Silver-sided Sector Spider." I recall this species being most abundant along the waterfront of the Columbia River when I was a child, but it is now among the most abundant of spiders even up in the hills of southwest Portland. It certainly associates itself with buildings, bridges, docks, and other structures.

What would these spiders feed on during the winter months? Many moth species fly throughout the colder months in the Pacific Northwest, plus winter crane flies, other dipterans, and some beetles. Orbweavers often crowd their snares around outdoor lights to further improve their odds of catching a meal.

Female with egg sac

Keep exploring during the winter months, even if it is only around the exterior of your home, office, or other building. You might well encounter one of these spiders, or any number of other organisms.

Sources: Adams, R.J. 2014. Field Guide to the Spiders of California and the Pacific Coast States. Berkeley: University of California Press. 303 pp.
Bradley, Richard A. 2013. Common Spiders of North America. Berkeley: University of California Press. 271 pp.
Sollfors, Stephan. 2010. "Zygiella x-notata," EuroSpiders.com
"Zygiella x-notata," NatureSpot.org.uk
"Summary for Zygiella x-notata (Araneae)," British Arachnological Society.

Underside of spider

Basket-web Weavers

Many spiders simply cannot be found easily during the day. One case in point are what I am calling "basket-web weavers" in the genus Calymmaria, family Hahniidae. There is no official common name for either the genus or the family, despite the fact that these are common and diverse arachnids.

During my recent visit to Portland, Oregon in December and early January, I made a point to look for spiders around the apartment complex where my late mother had lived. I was not disappointed. One of the most abundant spiders was some species of Calymmaria, though I was surprised by how many other spiders were still active in the relative cold, and certainly damp, weather that is characteristic of the Pacific Northwest at this time of year.

There are 31 species of Calymmaria found north of Mexico, all but two of which are found along the Pacific coast, east to the Cascade Mountains (some species in the Sierra Nevada Mountains). Those other two species are confined to the Appalachian Mountains.

The adults of Calymmaria measure 2-10 millimeters in body length depending on the species, and the ones I were finding were on the high end of that spectrum. In fact, at first I mistook them for members of the genus Tegenaria in the funnel-web weaver family Agelenidae. I learned while researching this post that indeed Calymmaria was once classified in the Agelenidae, and some species even placed in Tegenaria.

Calymmaria web on a fence

The webs of these spiders are truly unique. The bulk of the web is an inverted cone, anchored to a substrate both above and below. The spider also weaves a thin sheet close to the object from which the cone is suspended. Typically, the snares are built under loose bark, or in furrows in bark, beneath moss on rocks or logs, amid rocks by streams, under cliff overhangs, the entrances of caves, or even on buildings, which is where I found the spiders imaged here.

The spider emerges at night to hang beneath the sheet above the cone, though sometimes it may venture over the exterior of the cone. Prey is small insects, especially flies, which the spider attacks, bites, and retreats, maybe multiple times, before hauling the victim back to the platform web to feed.

The species I found is very likely C. emertoni, but without collecting adults, especially males, and examining specimens under a microscope, I cannot be positive. Calymmaria bifurcata is essentially identical save for subtle differences in their genitalia. Females of bifurcata range from 5.89-8.25 mm, while emertoni is 5.02-7.95 mm.

I grew up in Portland, in the very neighborhood I was visiting last month, but I never went prowling around at night, and therefore missed this particular spider altogether in my youth. Today, of course, I have to be cautious lest someone call the authorities for my suspicious behavior.

I still recommend that naturalists be nocturnal as well as diurnal. I try and make myself more conspicuous at night, though, figuring that someone with criminal intentions will be more furtive. I'll let you know how that turns out.

Sources: Adams, R.J. 2014. Field Guide to the Spiders of California and the Pacific Coast States. Berkeley: University of California Press. 303 pp.
Heiss, John Stabe and Michael L. Draney. 2004. "Revision of the Nearctic Spider Genus Calymmaria (Araneae, Hahniidae)," J. Arachnol. 32: 457-525.
Ubick, D., P. Paquin, P.E. Cushing, and V. Roth (eds.) 2005. Spiders of North America: an identification manual. American Arachnological Society. 377 pp.