Argiope Spiders

Late summer/early fall seems to be the season of spiders.  This time of year, it is difficult to walk through the woods, fields, or wetlands without wearing webs on your face and pants.  Some of the most common and conspicuous spiders that I notice this time of year are those in the genus Argiope.  Often called "garden spiders," these ~2" long (the bodies of the males are much smaller) yellow, black, and silvery white orb-weavers can be quite intimidating for those with even the slightest bit of arachnophobia, but unless you have six legs and a pair of antennae, you have nothing to fear.  A severly harassed female with an egg sac may bite a human, but the bite is said to be no worse than a bee sting.

Female Black-and-yellow Argiope.  Be sure to click on this photo to enlarge it so that you can see the characteristic zig-zag stabilimentum that she weaves into her web.

An interesting feature of the argiope spiders is that they weave a ribbon of silk called a stabilimentum into their webs; this stabilimentum is often in a zig-zag pattern.  Although entomologists cannot agree on the true purpose of the stabilimentum, there are several theories as to why argiope spiders expend energy to create them.  One possibility is that it adds to the stability of the web.  Another idea is that the stabilimentum is easily seen by birds and mammals that as a result avoid the web and therefore don't destroy it.  Others think that the structure helps to camouflage the spider, while some think that the stabilimentum may actually attract potential prey.  Regardless of its purpose, each species of argiope spider produces a distinctive stabilimentum that helps biologists distinguish between species by only looking at the webs.

There are five species of Argiope in North America, with a sixth (Bruennich's Argiope, Argiope bruennichi) potentially present in Alaska.  Of the five species in the continental United States, three have fairly restricted ranges.  The Silver Argiope (Argiope argentata) is primarily known from the southern parts of California, Texas, and Florida, as well as from Arizona.  A similar species, Argiope blanda, is known in the United States only from the southern tip of Texas.  Florida Argiope (Argiope florida) can be found in the southeastern United States, from North Carolina to Florida and west to Louisiana; it may also be found in Arizona.  The other two species are widespread.  The one I see most frequently is the Black-and-yellow Argiope (Argiope aurantia).

Female Black-and-yellow Argiope, dorsal side.

 Black-and-yellow Argiopes have a characteristic black and yellow pattern on the back of their abdomen, whereas the carapace is covered in silvery hairs.  The legs are mostly black but often have reddish or orangish coloration at the proximal end.  Black-and-yellow Argiopes also have distinctive yellow and black coloration on their undersides.  You can find this species of spider in old fields, wet meadows, riparian areas, and gardens.


Female Black-and-yellow Argiope, ventral side.

 The other widespread species is the Banded Argiope (Argiope trifasciata).


Female Banded Argiope, dorsal side.

 Banded Argiopes are identified by the yellow, black, and silvery-white stripes on the back of their abdomens.  Like the previous species, the carapace of this species is covered with silvery hairs.  The legs of the Banded Argiope are striped black and orangish-brown.  The underside of the abdomen of the Banded Argiope is also distinctively patterned with black and yellow.  You can find the Banded Argiope in grassy and shrubby areas that are usually a bit drier than where you find the Black-and-yellow Argiope, but the two can be found in the same area.


Female Banded Argiope, ventral side.

 One of my observational differences in the females of these two species is that the Black-and-yellow Argiope seems to drop from her web fairly quickly when I bump into it, whereas the Banded Argiope seems to hold her ground.

If you are one of those people who is deathly afraid of spiders, I hope that this at least gives you a better respect for the argiopes.  If you are one who likes spiders, be sure to get out in the next couple of weeks before it gets too cold to admire these large black and yellow arachnids.

Blue Curls Resurfaces

On a recent work trip in Muskegon County, Michigan, Linda VanAndel and I saw the State Threatened Blue Curls (Trichostema dichotomum) in bloom.  This annual mint has flowers that are small (only about 1 cm long) but that are quite interesting, with arching hair-like stamens (Trichostema in fact means "hair-like stamens") curled over the single lower lip.  Looking at the form of the flowers, you can see how the lower, purple-spotted lip serves as a nice landing pad for insects in search of nectar, while the curled stamens deposit pollen on the back of the oblivious feeding insect.  The style is also curled and arching, meaning that the next Blue Curls flower that the insect visits will be pollinated when the pollen on the insect's back rubs up against the receptive stigma.  This is an excellent pollination strategy, considering that bee species characterstically move from flower to flower of plants of the same species in search of nectar.

Blue Curls is known from many states and provinces in the eastern half of North America.  It grows in coarse, acidic soils in open areas including prairies, savannas, open woodlands, sandhills, and pine flatwoods.  Blue Curls relies on fire or other disturbance to persist as part of a local flora, as it is not tolerant of competition from other plant species.

Stable over its North American range, Blue Curls is also a species of concern in Indiana (State Rare).  The site where we saw it in Michigan was excavated a few years ago, creating disturbed, open soil that is ideal.  I have seen it at a few sites in Indiana, including one location in Porter County that historically was mined for sand and another along a recently excavated roadside berm in St. Joseph County (both, again, disturbed sandy soil).  The yet to be answered question is: where does this species come from when there is no apparent seed source and sandy soil is excavated?  Have the seeds been covered by years of sand and organic accumulation, just waiting for a disturbance to bring them back to the surface so that they can germinate?  Are the seeds brought in by excavating equipment?  My guess is the former, but then you have to wonder how long the seeds can remain viable.  Surely, it takes hundreds, if not thousands, of years for a foot or more of soil to accumulate, meaning that the seeds may remain viable for that long.  Nature is resilient.

Small Mammals That Excite Even A Wildlife Biologist

I apologize in advance for the poor quality of the two photos in this post, but I couldn't resist including them. Within a week's time, I saw two mammal species that made even esteemed Cardno JFNew wildlife biologist Jeremy Sheets giddy.

At a mitigation wetland at a landfill in Lake County, Indiana, I was sampling vegetation quadrats when I heard a Mallard smacking its wing against the water. I've seen Killdeer on many the occasion perform the "broken wing" routine when trying to keep a predator away from a nest, but I'd never heard of a Mallard displaying this behavior. Still, that was all that I could imagine was going on. The wing smacking continued, so I eventually walked in the direction of the noise, but the Mallard didn't leave the spot. As I got closer and the smacking stopped, I saw that the back of the Mallard's neck was covered in blood. Then I saw a small, dark mammal bound and scurry away through the several inches of water. I'd witnessed a kill! I followed in the direction that I'd seen the mammal go but I couldn't find it. Reluctantly, I went back to sampling without seeing the predator. Soon after, I heard rustling of vegetaton from the location of the dead Mallard. I snuck back over and again saw the dark mammal scurry away. I decided this time to stay close to the dead Mallard and wait to see if the culprit returned. Less than a minute later, I saw the killer, shown below.


This was my second ever live encounter with a Mink (Mustela vision), but my first encounter when I wasn't in a car. They live in areas where there is water, such as borders of lakes, marshes, streams, ditches, and ponds. Mink are omnivores, but nearly all of their food consists of other animals, and their preferred prey is Common Muskrat (Ondatra zibethicus). These dark-colored weasel relatives are also known to inhabit Common Muskrat dens and usually eventually drive these slightly larger mammals away. At this site, there were numerous Muskrats two years ago, but this year I saw only abandoned dens. Because of their typically nocturnal habits, Mink are often not observed by humans. Mink are found throughout much of North America, with the exceptions of parts of northern Canada and the southwestern United States.

My second mammal encounter occurred at a mitigation site in Superior, Wisconsin, while I was meeting with representatives from the U.S. Army Corps of Engineers and the Wisconsin Department of Natural Resources. As we were talking, the Corps of Engineers biologist saw a squirrel come out from under a parked vehicle.


This was my first ever encounter with a Franklin's Ground Squirrel (Spermophilus franklinii), a rare diurnal species restricted in range to east-central Alberta, southern Saskatchewan, and southern Manitoba south to northern Kansas, northern Illinois, and northwestern Indiana. At first, we thought we may be looking at a Gray Squirrel (Sciurus carolinensis), but this individual was smaller than a Gray Squirrel and had a gray head and gray tail with a brown body, and we later saw its burrow in the loose soil of an exposed mound of dirt. Franklin's Ground Squirrels feed on a mix of plants and animals, with green clover leaves being the primary vegetation and caterpillars and ants being the primary animals. They are found in dense grassy areas, often along railroads and on roadsides.

Another Successful Half Marathon

The morning of 14 August, we were in Chicago for the Rock 'n' Roll Half Marathon. Since Lindsay and her dad were running, I manned the camera.


The weather was quite pleasant, cool with a few short-lived showers during the day.


In the photograph below, Lindsay and Jack are approximately halfway done, still with enough energy to wave at the camera.


Below is a photograph at mile 13, with just 0.1 mile left to go!


Great job, Lindsay and Jack!


Chicago Rock 'n' Roll Half Marathon Finishers!

Fail, To Some Extent

I apologize for the delay between posts, but things have been pretty busy lately. Since the Thismia Hunt on 13 August, I've been in five states, including spending nearly a week and a half in Superior, Wisconsin. I'm back home, with plenty of blogging material... but first, a brief Thismia Hunt recap.


Unfortunately, this was the only Thismia americana that I saw on 13 August...


... and it was a lifesize model in a display at the hunt headquarters.


Our team of nine hopeful hunters (several of which are pictured above) spent the day at DuPont Nature Preserve in Gary, Indiana, scouring as much of the wet prairie habitat as we could in five short hours.


Paul Labus (above) of The Nature Conservancy knows this site better than anyone, and he took us to the most likely places where Thismia might occur.


Although our hunt for Thismia was unsuccessful, we were successful in seeing some pretty nice dune and swale habitat with wet prairie in the swales and savannas on the dunes. The wet prairie shown above seemed ideal for Thismia americana, as several of the species originally found growing with the tiny saprophyte were growing here. Our group tallied over 225 plant species during our surveys, which is fairly impressive since we probably only covered 1/4 to 1/2 acre thoroughly, plus our walk to and from the areas that we surveyed.


Another very successful aspect of the Thismia Hunt was the turnout of Thismia hunters. There were over 90 people searching for Thismia (including several very well known Chicago Region botanists) and celebrating 20 years of conservation in the Calumet Region on 13 August. Many of these were people I hadn't seen in a while, and others were new acquaintances.


I am already looking forward to the next Thismia Hunt, as I still maintain hope that it is out there, somewhere.

Hunting For A Ghost Plant

I have big plans for next Saturday, August 13, 2011. Along with numerous other botanists from the Chicago Region and beyond, I will be spending the day on my hands and knees in search of arguably the most intriguing plant species in the world, Thismia americana, as part of Thismia Hunt 2011. First observed in early August 1912 near Lake Calumet in Cook County, Illinois, observed and monitored for five straight growing seasons, and last seen in the wild in 1916, this tiny member of the mostly tropical family Burmanniaceae is far removed from its closest relative, Fairy Lantern (Thismia rodwayi), which grows only in Australia, New Zealand, and Tasmania. In fact, most of the plants in this family grow in rich, loamy primeval forests that receive large amounts of precipitation, and no other Thismia species are even known to occur in the temperate zone. Thismia americana has only ever been observed growing in two locations - the location of the original discovery and a site only approximately 1/3 mile away - and has not been seen alive since the year that the Chicago Cubs played their first game in Wrigley Field (then Weeghman Park).


Finding a plant that hasn't been seen in nearly a century is difficult enough, I should think. Add to that the fact that the entire plant consists of subterranean roots from which a short floral stalk arises, upon which a mysterious tubular flower up to at most 1.5 cm develops. Consider also that the translucent flower is mostly white with blue-green perianth lobes, and that only the pastel blue-green portion of the plant actually emerges from the soil between clumps of mosses. Also, if the phenology of Thismia americana is similar to that of its orchid-like relatives, it may not flower every year, or its flowers may persist fully underground. Taking all of these things into account, as well as the fact that during a Thismia hunt several years ago small white beads were randomly hidden and very few of them were ever found even after volunteer surveyors were told exactly where to look, isn't it possible that Thismia still exists somewhere, undetected for nearly 100 years? I certainly think so!


So who could have possibly initially discovered this saprophytic, nearly subterranean and leafless plant growing amongst the club moss Selaginella and the ground-hugging mosses Aneura and Hypnum beneath wet prairie species such as Sweetflag (Acorus americanus), Redtop (Agrostis gigantea), Swamp Milkweed (Asclepias incarnata), Common Boneset (Eupatorium perfoliatum), Grass-leaved Goldenrod (Euthamia sp.), Blueflag Iris (Iris virginica), Black-eyed Susan (Rudbeckia hirta), and Late Goldenrod (Solidago gigantea) in a remnant lake plain prairie of glacial Lake Chicago? It was none other than the sharp-eyed 23-year old University of Chicago botany graduate student Norma Etta Pfeiffer, who was on all fours searching for liverworts on that memorable August morning. As a result of her amazing discovery and subsequent research on the new-to-science plant she named Thismia americana, Pfeiffer just two years later became the youngest person to receive a PhD from the University of Chicago. Sadly, just two years after her initial discovery and the same year that the plant name Thismia americana was published, Pfeiffer returned to the site to find that a barn had been constructed on the site of her discovery. More recently, this area has been developed into an oil-tank storage area. Thismia was also observed by Pfeiffer in a second location which consisted of cattails (Typha sp.) in a swale between ancient beach ridges. It is unclear whether this location still exists in a natural state or if it, too, has suffered the fate of development.


To date, this is the closest I've ever been to Thismia americana - holding a 2-inch, glycerine-filled vial that contains (and even dwarfs) the miniscule plant. I hope that one day, maybe even next weekend, I will have the opportunity to experience living Thismia.


Please wish me (and all of the Thismia hunters) luck next weekend as we crawl around like ants beneath the tall prairie species searching for this lilliputian ghost plant.

That's One Big Caterpillar

While on Harsen's Island in St. Clair County, Michigan last week, Tony Troche found a thick, enoromous caterpillar. After a quick check on someone's fancyphone, we were able to determine that our caterpillar was that of a Cecropia Moth (Hyalophora cecropia).


A couple of years ago, Lindsay found a dead Cecropia Moth in our driveway. To see that post, which includes more information on the species, click here.

Harsen's Island Milkweeds

During the past two weeks, I had the opportunity to spend five days botanizing and doing rare plant surveys with several coworkers in the globally and state imperiled to critically imperiled Lakeplain Wet Prairie and Lakeplain Wet-Mesic Prairie communities on Harsen's Island in St. Clair County, Michigan. These communities have developed on glacial lakeplains and have an impermeable clay layer several feet below the sandy surface layer. This results in inundation in the winter and spring and very dry conditions later in the summer. One of the greatest threats to the remaining lakeplain prairies is invasive species... you can see this impending threat in the photograph below, where there is a dense wall of Common Reed (Phragmites australis) in the background, below the tree line.


Two of the plants of conservation concern that we were looking for on this site were milkweeds (Asclepias spp.). We saw numerous milkweeds on our site, including several common species and both of the rare species.


Swamp Milkweed (Asclepias incarnata) was one of the common species that we saw. As seen above the blossoms of this milkweed are bubblegum pink... and coincidentally they also smell like bubblegum! With its primary geographic distibution centered in the upper Midwest and New England states, Swamp Milkweed is known from most of the Lower 48, with the exceptions being Mississippi, Arizona, California, Oregon, and Washington. It grows in many different wet plant communities, including wet prairies, emergent marshes, swamp forests, bogs, and along streams and pond margins.


The milkweed above, Butterfly Milkweed (Asclepias tuberosa), grows in much drier conditions and often in well-drained sandy soils. You can find this handsome orange-flowered species growing in prairies and savannas as well as along roadsides and on glades throughout the eastern half of the United States and adjacent Canada, as well as in the southwestern United States. Unlike the other milkweeds, which have a white, milky latex, Butterfly Milkweed has clear sap.


Common Milkweed (Asclepias syriaca, above) was abundant on the site we investigated on Harsen's Island. Although it is an opportunistic native species that grows in heavily degraded areas, Common Milkweed also grows in various prairie types. The corolla of this species can be pink, as in the photograph above, or more cream-colored. Although its North American distribution includes 39 of the states in the contiguous United States, Common Milkweed is most abundantly distributed in the upper Midwest, the Great Lakes states, and New England.

Now for the species of conservation concern...


We saw numerous individuals and populations of Purple Milkweed (Asclepias purpurascens). As seen above, the corollas of this State Threatened species are a deeper pink than those of Swamp Milkweed or Common Milkweed, ranging even to reddish or purplish. The center of Purple Milkweed's geographical distribution is Missouri and Illinois, with peripheral populations scattered throughout much of the rest of the eastern United States and Ontario. St. Clair County, Michigan, where Harsen's Island is located, is approaching the northernmost limit of the species' distribution. Purple Milkweed is found in wet prairies, oak savannas, and glades, as well as on woodland borders and in thickets.


We also observed some stunning populations of Sullivant's Milkweed (Asclepias sullivantii), also known as Prairie Milkweed. With glabrous, ascending leaves that have a striking pink midvein, the large, pink corollas of this State Threatened milkweed don't need to be present to make a correct identification. Of the species of milkweed discussed in this post, Sullivant's Milkweed has the most narrow geographical distribution, being found in the prairie region of the Great Plains and the Midwest, north into Ontario. As the common name suggests, this attractive milkweed is a prairie obligate.

Unscathed... Mostly

Just as I was getting over the worst case of poison ivy that I've ever had (here's a hint, genius... don't weed whip poison ivy while wearing shorts and flip flops), I joined Scott Holaday and Lee Casebere last Sunday to check out a property near Culver, Indiana. Scott and Lee had visited this private tract in the spring looking for Four-toed Salamanders (Hemidactylium scutatum), and their description of the site, a swampy forest with a lot of ferns, sounded too good to pass up. Had I known ahead of time that there would be as much Poison Sumac (Toxicodendron vernix) as there was in this swamp, I still would have wanted to join Scott and Lee, but I'm not sure if Lindsay would have approved of me going.


Shortly after arriving, Lee found a mole salamander (Ambystoma) in the laterale-jeffersonianum complex, a group that is notorious for hybridization and that requires genetic analysis to accurately determine the species. This interesting complex of salamanders includes an all female triploid group that requires sperm from a male salamander from a related species in the same genus to initiate reproduction, but the sperm is often then discarded and no genetic material from the male makes its way into the offspring. This asexual form of reproduction is known as gynogenesis. The best that I can do is to say that this is either a Blue-spotted Salamander (Ambystoma laterale), a Jefferson's Salamander (Ambystoma jeffersonianum), or one of the Ambystoma hybrids.


Our focus quickly shifted kingdoms when Lee exclaimed, "Here's a Purple Fringed Orchid!"


When Scott and Lee first told me about this site, the possibility of finding Lesser Purple Fringed Orchid (Platanthera psycodes) amongst the Cinnamon Fern (Osmunda cinnamomea) and Royal Fern (Osmunda regalis) and beneath the Red Maple (Acer rubrum), Black Ash (Fraxinus nigra), and Swamp White Oak (Quercus bicolor) immediately registered. Little did I know, however, that we would find the largest population of this attractive orchid that any of the three of us had ever seen. Had I done my research ahead of time, I might have thought that there would be less of a chance of finding Lesser Purple Fringed Orchid on this site, even though the habitat was perfect, as it was not mentioned in the monumental 1920s work by Evermann and Clark on the physical and biological resources around Lake Maxinkuckee. In addition, none of the distribution maps that I've seen show this species in Marshall County, Indiana. This makes our finding of an estimated 50 to 100 Lesser Purple Fringed Orchid plants an even more exciting find, as well as a potential county record.


In addition to Lesser Purple Fringed Orchid, Cinnamon Fern, Royal Fern, Black Ash, and an abundance of Poison Sumac, some of the more uncommon plants that we discovered in this swamp forest included Slender Sedge (Carex leptalea), Bulblet-bearing Water Hemlock (Cicuta bulbifera), Crested Wood Fern (Dryopteris cristata), Pipes (Equisetum fluviatile), Floating Manna Grass (Glyceria septentrionalis), Winterberry (Ilex verticillata), Stalked Water Horehound (Lycopus rubellus), Canada Mayflower (Maianthemum canadense var. canadense), Chokeberry (Aronia prunifolia), Dwarf Raspberry (Rubus pubescens), Great Water Dock (Rumex orbiculatus), Rough-leaved Goldenrod (Solidago patula), Skunk Cabbage (Symplocarpus foetidus), Highbush Blueberry (Vaccinium corymbosum), and Smooth White Violet (Viola blanda).


After sludging through mucky soils, swatting at bloodthirsty mosquitoes, losing a gallon of sweat, and brushing up against Poison Sumac plants while trying to squeeze between them, I was convinced that the title of this blog post was going to be "Worth The Rash." Luckily, it appears as though I've escaped with only a small spot of the nasty underneath my left eye. To see 50 to 100 Lesser Purple Fringed Orchids, a single spot of poison sumac is definitely acceptable.

It's Like Looking In A Mirror

In June, Lindsay and I, joined by Lindsay's parents, took a vacation to Costa Rica. This was our second visit to the rich coast, and this time our travels took us to Guanacaste on the Pacific side of the country. We are still going through photos, so more will show up here as we have time to get through them all.

On our first visit to Costa Rica back in 2007, the hatching Green Sea Turtles were the overwhelming highlight of our trip. This time, though, the primates provided some of the most memorable moments. We saw three of the four species of monkeys that Costa Rica has to offer; we did not see the smallest species, Central American Squirrel Monkey (Saimiri oerstedii), and we didn't get photographs of the largest species, Geoffroy's Spider Monkey (Ateles geoffroyi). The three species that we saw all have prehensile tails that are used as one-fingered fifth limbs, allowing them to move with swift agility through the treetops.

Nearly every day on our week-long trip, we heard the grunting and roaring of Mantled Howler Monkeys (Alouatta palliata) from our hotel room. We also saw these large platyrrhines on three or four occasions during our day trips. Our best looks were along our drive to a boat tour through Palo Verde National Park on the Tempisque River. Mantled Howler Monkeys have a geographical range from Mexico to Ecuador and live for up to 15 to 20 years.


Some sources consider Mantled Howler Monkeys the largest species of monkey in Costa Rica, at least by weight, as large males can weigh up to 22 lbs. Other sources say that this species only gets to 16 lbs., and that therefore the Geoffroy's Spider Monkey, which gets up to 18 lbs., is the largest monkey in the country. Geoffroy's Spider Monkeys are more slender than Mantled Howler Monkeys, however. Mantled Howler Monkeys are strictly vegetarians that live in groups usually ranging from four to 40 individuals. These groups have home ranges of 25 to 150 acres. The adjective "howler" in the common name of this species comes from the loud noises that are made by the males (most often at surise and sunset) to communicate with group members and define territories; these communicating sounds can be heard up to three miles away. When disturbed by people, Mantled Howler Monkeys are known to throw feces with precise accuracy.

While on our boat tour at Palo Verde National Park, we had some nice looks at White-faced Capuchins (Cebus capucinus). This species is known from Honduras to Ecuador and has a life span of more than 50 years.


White-faced Capuchins, also known as White-headed Capuchins, are middle-of-the-road in terms of size in relation to other Costa Rican monkeys, weighing approximately 8 lbs. Unlike the Mantled Howler Monkey, White-faced Capuchins are omnivores, feeding on fruit, leaves, insects, and even small mammals and other vertebrates. They live in troops that can consist of up to 40 individuals and have home ranges of 79 to 210 acres. Whereas Mantled Howler Monkeys have not been observed using tools, White-faced Capuchins, which are said to be highly intelligent, have been seen using tools to obtain food and as weapons, and they also apparently use certain plants as herbal medicines by rubbing them on their fur. White-faced Capuchins get their common name from the resemblance of their coloration to the cowls worn by Capuchin friars. If you have seen the Friends episodes where Ross has a pet monkey, this species likely looks familiar to you, as Marcel was a capuchin monkey.

Stay tuned for more photographs and commentary from Costa Rica.