Get to know some local chelicerates, from spiders to scorpions and pseudoscorpions

This is an excerpt from my article in the September – October issue of Triangle Gardener magazine, available at local libraries, the NC Botanical Garden, plant nurseries, etc. and posted online at www.trianglegardener.com. This is the last part of the article. Also, the annual Big Sweep and UNC University Day trash clean-ups are coming up in October. Late September also seems to be the season when copperheads get on roads at night, often in the same places every year, and then can’t or won’t avoid traffic, possibly because they get too cold, and get killed. I carry a metal grabber so I can safely remove copperheads, but I often come across them too late. Note that people have been ‘bitten’ handling dead snakes.

I doubt that arachnophobia is innate, but I have long been disturbed by spiders. I used to be a bit creeped out just looking at the photos in the Audubon guide to insects and arachnids. When I was very young there were large, striped spiders in my backyard, perhaps rabid or dotted wolf spiders, and unfortunately I tried to kill them. I don’t remember going out of my way to knock down webs and some arachnids and spiders were less unsettling. I wasn’t really afraid of omnivorous daddy longlegs, also known as harvestmen or shepherd spiders, though I think I was bitten once. NC has many species of daddy longlegs. Later I volunteered in UNC’s invertebrate biology lab, and was asked if I wanted to hold the hairy, palm-sized tarantula. It had its legs tucked in and didn’t move, so it wasn’t very trying. On the other hand last fall I was disturbed when a brown orbweaver, spinning its, probably her, web at the front door on a breezy evening suddenly dropped down to anchor a line, revealing just how large and ‘spidery’ she was, legs outstretched. A few weeks ago I saw a pretty large wolf spider indoors. I was preoccupied at the time, so I let it stay inside temporarily as a beneficial animal, but I haven’t seen it since.

Insects have three body sections and six legs with five parts, while spiders have two body sections and eight legs, with seven parts. Crustaceans are arthropods with 10 legs and four antennae, but are accepted as food animals. Insects generally have a pair of compound eyes and three smaller simple eyes, while spiders have at most eight simple eyes, the arrangement and acuity varying by family. Moving a pencil tip around a corner attracts a sharp-eyed jumping spider, like a curious cat. Jumping spiders might also tend to be more intelligent than most spiders, especially those that specialize in hunting other spiders. Spiders use ‘hairiness’ for functions like sensing, in the absence of antennae; defense; etc. Spider chelicerae end with sharp, venom-injecting fangs and are sometimes toothed. The chelicerae and pedipalps just behind rub together to grind up prey, but spiders typically only consume pre-digested juices. Some spiders are actually omnivorous or even mostly herbivorous. Males can be identified by their clubbed pedipalps, used in mating. Many spiders engage in courtship and in most species males survive the attempt. It seems like arachnids are often longer lived than insects and spiders often mature later in the growing season. Spiders can go to an exposed point, such as the roof of a car, and release a long silk thread to catch the wind and balloon to a new location. Spiders typically make several kinds of silk, even a silk just for egg sacs. Medicine spider silk was once used to make a painkiller and clothes, bandages, and canvases for painting have been made with spider silk.

The NC Biodiversity Project website lists 713 arachnids in the state. LL Gaddy estimated in 2009 that there are around 600 spider species in the Carolinas. The Tuscarora orbweaver is only found in NC, including in Durham County. The spruce-fir moss spider is an endangered species found on peaks in the Appalachians.

At Falls Lake State Recreation Area there are black trapdoor spiders of some kind, resembling tarantulas. Actual tarantulas are considered a normal food animal in some cultures. Huge dark fishing spiders live around the park buildings, where I saw one kill an adult Carolina mantis. Smaller and more aquatic six-spotted fishing spiders, which actually have more than six spots, might be seen around Parkwood’s Euclid Pond on summer days, delicately moving on and sometimes under the surface. Species of elongated long-jawed spiders typically build their webs in vegetation at the edges of ponds and are common in the area.

Once I got lost in a scrubby forest behind Kure Beach, between Wilmington and the end of the Cape Fear River, where the water from Northeast Creek meets the sea, and was struck by the many large brown and yellow butterflies, probably giant swallowtails, flitting about. I was also struck by the numerous boxy webs inhabited by very large female golden silk orbweavers and much smaller males. It seemed like the spiders weren’t catching the similarly huge swallowtails, but I have seen other orbweavers capture a swallowtail or cicada. Golden silk orbweaver build their webs in stages and refurbished them a half at a time. I think I read that they have been found in Raleigh, but these spiders might have been brought back by vacationers. On the other hand with a warming climate they might extend their range inland. Southeastern NC is at the northern limit of their range, which extends to the Amazon. Male spiders often live near or in webs spun by females, but truly social spiders are limited to the tropics. There is also the case of introduced snakes killing off native birds in the tropical Pacific, leading to forests abnormally full of solitary spider webs.

Another large orbweaver is the yellow garden spider, known for the stabilimentum, a jagged line down their webs. In recent years I had some, the males staying near the females. One morning last summer a wrapped up and stored away and May beetle was waving a backleg and I peeled off the silk and freed it , apparently unharmed, but afterward the female left, as if taking umbrage, followed by her retinue, and I haven’t seen any since.

There are still one or more large brown nocturnal orbweavers, maybe Neoscona species, though it seems like they were more abundant many years ago. I saw one or two near porchlights over the summer, but not in recent weeks. Occasionally the large orbweavers are joined by much smaller conical spiders colored like liquid mercury, species of Argyrodes, co-habiting the webs as kleptoparasites, feeding on caught insects and possibly also on the orbweavers when they die in the fall.

Several smaller orbweavers can be seen during the day in wooded areas and yards and their webs can stick to people in late summer. This summer I noticed a few spiny orbweavers, white or yellow with somewhat colorful spots and ‘spines,’ the harmless spikes possibly providing some protection from birds. Their webs have prominent white dashes around the edges and in the center. More familiar Micrathena orbweavers are also spiny. It seems like triangulate orbweavers or something similar like to place their large webs across bottomland clearings. Triangulate orbweavers have a prominent white, yellow, or pink triangle on the top of their abdomen. Conical trashline orbweavers leave a vertical line of silky debris in their webs.

I sometimes see widows in webs around house foundations and in outbuildings. Female Northern and Southern black widows are large and black with bright red markings, but the smaller males look different and brown widows are moving north. Unrelated brown recluses are apparently not native to the Carolinas and are rare. These are the only venomous spiders regularly found in the Carolinas whose bites might cause serious effects. Some spiders are physically unable to bite humans and in general venomous animals won’t bite or sting if left alone and if they do, some have the option of injecting little or no venom.

I occasionally see green lynx spiders, relatively large and bristly spiders that hunt on plants, females turning from bright green to brown in the the fall. Aparently green lynx spiders fill an ecological niche similar to that of crab spiders. I see various crab spider species more often, usually lying in a wait on an upper leaf or flower, where they can be very colorful for camouflage.



Some resources:


Spiders of the Carolinas LL Gaddy, 2009

The Audubon Guide to North American Insects & Spiders [and other arachnids] Lorus and Margery Milne, 1992

North Carolina Biodiversity Project – Arachnids – www.nc-biodiversity.com/taxonomic-group/arachnids

Arachnids of NC, from the above site – auth1.dpr.ncparks.gov/arachnid/index.php .

Arachnids of NC checklist – auth1.dpr.ncparks.gov/arachnid/checklist.php?format=pdf

Biology of the Invertebrates, Fourth Edition Jan A Pechenik, 2000

The Life of the Spider John Crompton, 1954 – anecdotes

eco.confex.com/eco/2008/techprogram/P12401.HTM – a mostly vegetarian Central American jumping spider – information at the 93rd annual meeting of the Ecological Society of America

A review of the ethology of jumping spiders (Araneae, Salticidae) David B Richman and Robert R Jackson, 1992 – www.peckhamia.com/hosted/Richman%20Jackson%201992%20A%20review%20of%20the%20ethology%20of%20jumping%20spiders.pdf

Pseudoscorpions of the World – museum.wa.gov.au/catalogues/pseudoscorpions

Spiders of North-West Europe – ednieuw.home.xs4all.nl/Spiders/spidhome.htm

World Spider Catalog – wsc.nmbe.ch/statistics/

Global Biodiversity Information Facility – www.gbif.org

BugGuide – www.bugguide.net/

American Arachnological Society – Americanarachnology.org

International Society of Arachnology – arachnology.org

The Arachnid Order Solifugae – www.solifugae.info/index.html

AracnoLab – Aracnologia MNRJ – Museu Nacional/Universidade Federal do Rio de Janeiro – mndi.museunacional.ufrj.br/aracnologia/ – on daddy longlegs, harvestmen, or shepherd spiders

Jumping spiders (Arachnida: Araneae: Salticidae) of the world –www.jumping-spiders.com

International Field Guides – find a field guide by subject or region – www.library.illinois.edu/biology/fieldguides/

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