Spider Sunday: Red Velvet Jumper

Whenever I discover a species new to me, I am compelled to illuminate the known biology of the organism for anyone who will listen, or read. This happened recently, when I encountered a little jumping spider on a sidewalk during a late afternoon walk here in Leavenworth, Kansas, USA, on August 20.

I managed to capture the creature in a plastic vial, to take home for closer observation. At the time, I anticipated that it would be an immature male in the genus Phidippus, as they are common, especially along this pathway through lawn and wannabe prairie that parallels a major street on the north end of town.

I am prone to neglecting or procrastinating in taking photos of captive specimens, so it was August 25th before I finally sat down for a spider photo shoot in the white casserole dish we have dedicated as a “studio” for insects and arachnids. I was fortunate the spider was still alive, albeit perhaps a little more slender than when I first found it.

Throughout the process of capture and photography, the spider was surprisingly slow, which is not at all like most of the fast, bouncy jumpers that I am familiar with. Viewing my photos, it became apparent that whatever this spider was, it was a mature male (fully formed terminal segment on each pedipalp); and it lacked the iridescent chelicerae (jaws) of most Phidippus species.

Puzzled, I uploaded some of the photos to my Facebook page in hopes that some of my friends who are spider experts might be able to point me in the proper direction. It was after posting that I tried looking in some of my books to see if there was anything remotely similar to my specimen. The family Salticidae is highly diverse, and not every book about spiders will include every genus, let alone species. This time I got lucky.

I soon received replies to my social media post, the first of which was from Sarah Rose, author of Spiders of North America from Princeton University Press. That field guide does not include the species she suggested: Ghelna canadensis, but I reached the same conclusion in perusing Common Spiders of North America by Richard A. Bradley. Ian Wright also suggested the genus in his comment on the Facebook post, and Alicia Lips and Dani Marie agreed. Alicia included images of a female of the species that she found on her front porch in June of this year.

Ok, more about the actual spider. The community science platform iNaturalist gives a common name of Three-lined Ground Jumping Spider for Ghelna canadensis. Somewhere I recall reading the name “Red Velvet Jumper,” but that could apply to many other species, even though it is appropriate to the color and texture of this one. Most sources offer no common name. Mature males measure 4-5 millimeters in body length, females 4.6-6.4 mm. Females are darker, gray or brownish, with indistinct markings.

This is a ground-dwelling species, unusual compared to the arboreal species in its cohort, the subtribe Dendryphantina. It occurs over much of the eastern United States, except for the southernmost tier. Data points on iNaturalist have it as far west as Minnesota in the north, and near Dallas, Texas in the south. The "Checklist of Kansas Jumping Spiders" mentions records in Douglas and Jefferson counties, but not Leavenworth. Older references may use the former name, Metaphidippus canadensis. There are also three other species in the genus Ghelna, at least one of which, G. barrowsi, also occurs in my area.

After I finished the photo session, I provided the spider with some water from the tip of a soaked cotton swab. He was thirsty! Then I took him back to where I found him, releasing him well off the sidewalk this time.

Sources: Bradley, Richard A. 2013. Common Spiders of North America. Berkeley: University of California Press. 271 pp.
Guarisco, Hank, Bruce Ctuler, and Kenneth E. Kinman. 2001. “Checklist of Kansas Jumping Spiders,” The Kansas School Naturalist 47(1): 1-13.
World Spider Catalog
GBIF
Bugguide

Spider Sunday: Star-bellied Orbweaver, Acanthepeira stellata

NOTE:Today's post is an update of a previous post on November 11, 2012, prompted by a surprising recent find in our own back yard, on June 22, here in Leavenworth, Kansas, USA. I habitually tour our property looking for insects, spiders, and other invertebrates, and almost dismissed a brown, thorn-studded object as a piece of plant debris that had become adhered to our siding. Fortunately, I had seen other individual Star-bellied Orbweavers previously, though none of them nearly as large as this one.The hard, spiked abdomen of this adult female was nearly the size of a dime.

Nothing to see here....Psst, she's facing southeast

There is no shortage of the weird in the spider world, and this animal is a stunning example. One of my friends on the photo-sharing site Flickr asked "Why is it 'star-bellied' when it's star-butted? Is there more star-ness on its belly?" Fair question, to which I have no answer. Maybe the person that first saw one described it from the ventral side. The pointy tubercles certainly show up from all angles. The spikes enhance its camouflage as it passes itself off as a bur, seed pod, or bit of dried vegetation.

She has legs!

Acanthepeira stellata is one of four North American species in the genus, collectively found from southeast Canada south and west to southern California. This species in particular is known from southeast Canada to Florida, and west to Kansas and Arizona.

An immature spider in its web in western Massachusetts

These are not large spiders. Mature females measure 7-15 millimeters in body length, males 5-8 millimeters. Their unique appearance may make them easy to identify, but quite difficult to find, unless they are sitting in the hub of their web, which they don't seem to do with dependable regularity. Couple their cryptic shape with the fact that they tend to build their circular snares less than three feet off the ground in prairies, fields, meadows, and forest openings, and it can be an exercise in futility to hunt them amid tall grasses. Should one degtect your approach, it will drop to the ground, fein death, and disappear in the tangle of vegetation.

Can you spot the spider at Thoh-Dah Prairie in Missouri?

Star-bellied spiderlings emerge from egg sacs in summer, and overwinter as immature or penultimate (one molt removed from adulthood) individuals. Adult females can be found from May to October, at least in Illinois (Moulder, 1992). Mature males can be seen from May to September. I have found near-adults in odd places, probably as a result of "ballooning." Ballooning is a dispersal strategy used by many young spiders to travel afar and stake out their own territories. A spiderling typically climbs up to the summit of a tall object, stands on tiptoe ("tip tarsus??"), and issues long strands of silk from its spinnerets. These threads are caught by the wind, and when the spider lets go it may be blown hundreds of feet, if not a mile or more. One baby A. stellata was captured at 1000 feet in the air over Tallulah, Louisiana, on December 13, 1930 (Fitch, 1963).

This little one has ballooned onto the beach at Cape May, New Jersey

Once settled, these spiders spin the characteristic orb web to snare insects, mostly immature grasshoppers. There is one record of an adult female preaying upon an American Green Tree Frog, Hyla cinerea, but this is certainly not a routine event (Lockley, 1990).

An adult at night in Broken Bow, Oklahoma

Star-bellied Orbweaver is not immune to predators itself. The Black and Yellow Mud Dauber, Sceliphron caementarium, is a parasitoid wasp that stings spiders into paralysis and stockpiles them in mud cells as food for a single larval wasp in each cell. The wasps are undeterred by a hard-bodied spider.

Subadult spider in its web at night in Adams County, Ohio

You may have better luck finding the Star-bellied Orbweaver at night. Many species of orbweavers that are in hiding by day move to the hub (center) of their webs after dark. Taking a night hike reveals another world anyway, nocturnal spiders being among the impressive highlights.

Sources: Guarisco, Hank. 2017. A Pocket Guide to Common Kansas Spiders. Wichita, Kansas: Great Plains Nature Center. 67 pp.
Fitch, Henry S. 1963. Spiders of the University of Kansas Natural History Reservation and Rockefeller Experimental Tract. Lawrence, Kansas: University of Kansas Museum of Natural History, Misc. Publ. nol 33. 202 pp.
Gaddy, L.L. 2009. Spiders of the Carolinas. Duluth, Minnesota: Kollath+Stensaas Publishing. 208 pp.
Lockley, T.C. 1990. "Predation on the green treefrog by the star-bellied orb weaver, Acanthepeira stellata (Araneae: Araneidae)," J. Arachnol. 18(3): 359.
Moulder, Bennett. 1992. A Guide to the Common Spiders of Illinois. Springfield, Illinois: Illinois State Museum Popular Science Series, vol. X. 125 pp.
Weber, Larry. 2003. Spiders of the North Weoods. Duluth, Minnesota: Kollath+Stensaas Publishing. 205 pp.

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

The Tarantula Hunt

Heidi and I had the pleasure of going on a hunt for tarantulas on Labor Day, September 7, with Megan Miller, Jordan Spalding, and Bell Mead. Thanks to Ryan Nefcy, we learned of a location in Pueblo County, Colorado where one can reliably find tarantulas, genus Aphonopelma. Not only did we have success, but we found some other spiders, too, as well as some spectacular grasshoppers.

There are at least four species of tarantulas found in Colorado, and although we suspect the ones at the Pueblo County location are Aphonopelma hentzi, we would need to perform invasive procedures on a spider's genitalia to know for certain. The single specimen Megan collected is alive and well as we speak.

Occupied tarantula burrow

Bell has a keen eye for detecting tarantula burrows, which are surprisingly small and cryptic, hidden among tangles of desert grassland vegetation. Occupied burrows are covered with a thin film of silk by day. Sometimes, the remains of insect prey are scattered around the burrow entrance, too. Still, it takes skill to spot the holes.

Bell "fishing" for a tarantula while Heidi looks on

It takes even *more* skill to "fish" the occupant from her lair. Bell is highly skilled at this, and Jordan was able to capture the procedure in a video. Everyone was shocked to see such a large arachnid erupting from such a small tunnel. Whether a given spider is mature or not is difficult to assess. Male specimens change drastically in appearance upon their final molt into maturity, but females do not; and tarantulas are among the very few spiders that continue to molt after they reach adulthood.

Megan admiring the spider that Bell fished out

Megan's tarantula up close (© Megan Miller)

Upon returning home, Megan set up a spacious terrarium to house her new friend. Since tarantulas are in high demand in the pet trade, we agreed that we would not disclose the exact location that we visited. We thank Ryan for sharing his "spot" even with us. Thank you for trusting!

Megan's tarantula (© Megan Miller)

We found three occupied burrows altogether, but could only lure the one spider out. We did find other kinds of spiders, though. Before we had even ventured from the vicinity of our parked cars, we came across a lovely orange jumping spider, Phidippus apacheanus. It is thought that this species might mimic velvet ants, wingless female wasps that pack a very painful sting. They certainly share the wasp's bright "warning colors" of black and orange.

There were also Western Black Widows, and two kinds of orbweavers. This Banded Garden Spider, Argiope trifasciata was a highlight of the trip. Despite her size she was difficult to spot in her web in dense, tall grass.

Banded Garden Spider

Heidi had an easier time noticing another giant, a female Black and Yellow Garden Spider, Argiope aurantia. This species seems to prefer slightly more "open" situations, but still build their webs relatively close to the ground. Both species of Argiope can easily handle grasshoppers and other large, strong prey that become entangled in their snares.

Black & Yellow Garden Spider

Grasshoppers certainly were plentiful, and diverse. They scattered at every step: Carolina Grasshopper (Dissosteira carolina), Two-striped Grasshopper (Melanoplus bivittatus), and Two-striped Mermiria (Mermiria bivittata) being among the most conspicuous. I also finally got images of the Ebony Grasshopper, Boopedon nubilum, and Saussure's Blue-winged Grasshopper, Leprus intermedius. Black-winged Grasshoppers, Trimerotropis melanoptera,also made an appearance.

Leprus intermedius with hind wing spread

As we were leaving, Jordan suddenly jumped and exclaimed that a very large insect had collided with him after it leapt from the ground beneath his feet. Upon investigating we found a spectacular female specimen of the Green Bird Grasshopper, Schistocerca shoshone. This was the first one I have seen in Colorado.

Green Bird Grasshopper

We concluded our expedition with a well-earned visit to the Dairy Queen back along the interstate at Pueblo. As we sat down I noticed a small spider on the outside of the window. Tired and hungry, I nearly dismissed it as "just another orbweaver." I am glad I took time to double check. It was a mature pirate spider, family Mimetidae, perhaps Reo eutypus, though I can't be positive. You just never know *what* you will find, or where you will find it! Many thanks to my partners in crime. You all rock.

Pirate Spider from Dairy Queen

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.

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.

Large Hammockweb Spiders: Pimoa

One of the spiders I vividly recall from my childhood in Oregon is a species of large hammockweb spider in the family Pimoidae, genus Pimoa. They were once part of the sheetweb weaver family Linyphiidae, but among other differences they are w-a-a-a-y bigger than your average linyphiid.

The spiders themselves measure from 5 millimeters (males) to 12 millimeters (female) in body length. Their legs are pretty long, so they appear even larger. The common name could also apply to their webs. Sometimes they can span over one yard (yes, that's three feet). I have never seen a snare that large, and in fact, considering the size of the occupant, most webs are rather small, say no more than six inches across.

Pimoids are found only along the Pacific coast of North America, the Cantabrian Mountains (Spain), Alps, and Himalayas. There are twenty-one known species of Pimoa, about 15 species in North America north of Mexico. They seem to be spiders of the coniferous forests in the "rain shadow," at least from my experience in Oregon.

Immature(?) male Pimoa sp.

Look for their fine, net-like, horizontal webs issuing from crevices in logs, or, frequently, fences and retaining walls. It helps if there is a little dew. Otherwise the webs are surprisingly nearly invisible. The owners hide in a crevice or other retreat during the day, but can be seen hanging from the underside of the snare at night or even on overcast days.

Females make nearly spherical egg sacs that they cover with debris as camouflage. The number of eggs varies from about 80 to 100.

Like their relatives in the family Linyphiidae, large hammockweb spiders may break their legs off below the patellar (knee) segment to escape predators. This hardly compromises their agility, as you can see in the topmost image.

Next time you find yourself on the West Coast, take time to look for these interesting arachnids. I have to admit they are one of my "sentimental favorites."

Sources: Bradley, Richard A. 2013. Common Spiders of North America. Berkeley: University of California Press. 271 pp.
Hormiga, Gustavo. 1994. "A Revision and Cladistic Analysis of the Spider Family Pimoidae (Araneoidea: Araneae)," Smithson. Contrib. Zool. No. 549. 104 pp.

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.