Category Archives: Spiders

The world spider catalog, version 9.0. American Museum of Natural History

Platnick, N. I. 2008. The world spider catalog, version 9.0. American Museum of Natural
    History, online at http://research.amnh.org/entomology/spiders/catalog/index.html

The World Spider Catalog is a thorough catalog of the scientific literature regarding spiders, with a special attention paid to classification and taxonomy. 

The organization of the entries is hierarchically determined; hence synonymies at the
    generic level are indicated under the family (and cross-referenced under the appropriate
    generic) listings, but affected species are listed separately only if there are significant
    references to them in particular. Similarly, synonymies at the species level are listed under
    generic, rather than familial, headings. Unlike Roewer and Brignoli, I have not attempted to
    segregate species within large genera on a geographic basis. Their listings are often
    confusing, with widespread species being hard to locate and easy to overlook. Spider
    systematics has suffered too much from narrow regionalism to encourage strictly faunistic
    approaches in any way! The brief descriptions of geographic ranges are provided only as a
    general guide; no attempt has been made to ensure that they are comprehensive.

Cataloging the world’s spiders is hard work, and this collection lists (at the current reading) 3694 genera and 40462 species.  Unsurprisingly, then, you’ll need to go elsewhere for pictures and descriptions, but the exhaustively complete bibliography going back to 1757 will get you started.  1757?  Yes, 1757.  The oldest spider so cataloged is Salticus scenicus, which is pictured here (photo IvanTortuga), the zebra spider
The cite is

Clerck, C. Svenska spindlar, uti sina hufvud-slågter indelte samt under några och sextio särskildte arter beskrefne och med illuminerade figurer uplyste. Stockholmiae, 154 pp.

A researcher in the field of spider ecology notes that the presence of such detailed taxonomic bibliographies has greatly influenced spider taxonomic work, even when similar pre-electronic spider ecology work has been largely forgotten.  From James Bell, THE EMERGENCE OF MANIPULATIVE EXPERIMENTS IN ECOLOGICAL SPIDER RESEARCH (1684–1973)

In this review, the aim is to trace the early
advances in spider ecology to individual authors who were instrumental
in shaping our current understanding of ecology as a modern science.
The motivation for this paper is to reveal to the ecological community
some of the best early research in the first half of the 20th century
when it is believed that ecological spider experiments really began.
This period has remained elusive to most researchers, because the
majority of ecological literature pre-1970 is not available
electronically and ecological research tends to have a short citation
life-time which rarely extends beyond a decade. For example, there are
two excellent, but very similar experiments on orientation in Frontinella communis (Hentz 1850) (Linyphiidae). The first by Pointing (1965) was not picked up by Suter (1981)
or those who did the peer review and editing, simply because the
reference was not in general electronic circulation (Robert Suter pers.
comm.). This is not especially embarrassing because for most authors
there has rarely been a need to look deep into the scientific
literature—in fact, ecological journals positively discourage it.

Platnick, N. I. 2008. The world spider catalog, version 9.0. American Museum of Natural
    History, online at http://research.amnh.org/entomology/spiders/catalog/index.html

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Pumpkin spider, Araneus trifolium

From my inbox:

My name is Sarah and I’m 12. I live in Ann Arbor. Recently, my family found a spider
with a body about 3/4 an inch in diameter and with legs it was bigger
than a quarter. It is so huge! It is living in a big web between my
house and some bushes. The web is made up of circles and the spider is only there during evening and night. We think it hides in the bush the rest of the day.
    After we found it I did a lot of research and I am pretty sure that it is an Araneus trifolium (Pumpkin Spider, shamrock spider).
It has the rings around the legs and is the right size. It is in the
right time of year, has the right type of web, and has the right kind
of behavior.
    I don’t know whether it’s male or female. How do I figure out? Are
Araneus Trifolium poisonous? Are they common where we live? Can you
look at the pictures and figure out if I’m right and it is Araneus
trifolium? (they are attached)

and my response:

Hi Sarah,

Thanks for the pictures of your spider.  It looks like it is enjoying this time of year! 

Pumpkin spiders are very common this time of year, and they are found all over Michigan.  Spiders can be very hard to identify from photos, because there are so many species of them, but it seems that you have made a good identification.

The reference I’m looking at is

http://www.canadianarachnology.org/data/spiders/15257

Shorthouse, David P. submitted. Taxonomic and natural history description of FAM: ARANEIDAE, Araneus trifolium (Hentz, 1847). In: The Nearctic Spider Database. David P. Shorthouse (editor). World Wide
Web electronic publication. Direct link: http://www.canadianarachnology.org/data/spiders/15257 (Accessed:
9/28/2008 10:55:02 PM).

which describes both males and females of this species.  From that page it seems that females are more often seen later in the season, that they are larger than the males, and that their distinctive leg rings ("annulations") are more distinctive than the males.  So I’m guessing that it’s a female, but you
should try to measure its size to compare against that reference.  (One way to do that in photos is to put something of known size, like a coin, next to the spider when you photograph it.)

A second reference is

http://bugguide.net/node/view/11644/bgpage

which is the Bug Guide, which is hosted by Iowa State University Entomology. They have lots of pictures, as well as an identification service.  Their photos match up with your photos so you’re again probably confirming that identification.

As to the question of danger from spider bites, the Michigan DNR has a page on insects and spiders:

http://www.michigan.gov/dnr/0,1607,7-153-10370_12145_12204—,00.html

which talks about the two known spiders of medical importance in Michigan, the Northern Black Widow and the Brown Recluse.  Since it’s not one of those, you shouldn’t worry about it being dangerous.  In fact I searched google for the phrase

"pumpkin spider bites"

and got no hits.  You might find this search interesting too:

http://www.google.com/trends?q=pumpkin+spider&ctab=0&geo=all&date=all&sort=0

which shows that people look for pumpkin spiders this time of year!

thanks

Ed

(awaiting permission for use of the photos)

Very rare southern black widow spider bite in Michigan

Brad Gregory of Belding, MI (about 30 miles NE of Grand Rapids, MI) was bitten by a southern black widow spider (Latrodectus mactans Fabricius) on September 7, 2008.  The spider was found inside a Maytag dishwasher that his grandparents had purchased at Home Depot two weeks earlier.  He was treated at Spectrum Health System’s Blodgett Hospital in East Grand Rapids, which had the antivenin on hand.

The best news article on this is from the Greenville, MI Daily News, which also includes a picture of Brad holding the spider in question.  A quote from this article:

Doug Reeves,
assistant chief of the Michigan Department of Natural Resources’
Wildlife Division, said he’s seen about seven northern black widows,
"usually when I’m digging around woodpiles."

"They’re not particularly rare but they’re not something that’s found, unless you look in the right habitat," Reeves said.

Doctors told Gregory that his was one of only one or two southern black widow bites ever recorded in Michigan.

"They told him he would have a much better chance of winning the lottery," Margaret Gregory said.

Reeves
said he’d never before heard of a southern black widow bite in the
state. However, Reeves said he’s heard of other cases where non-native
spiders and snakes have come into the state through international
shipments, as was the case with Brad Gregory and his southern black
widow.

The southern black widow spider is not a common Michigan spider.

Some more reading:

Latrodectus mactans on the Animal Diversity Web, a good survey, on its habitat:

A terrestrial environment is the habitat of the Latrodectus mactans.
It is ubiquitous and builds strong-walled retreats quite close to the
ground and in dark sheltered spots. However, it also spreads its snares
over plants. Webs of the black widow spider can be found in recesses
under stones or logs in a woodpile, in crevices or holes in dirt
embankments, in barns and outbuildings. They can also be found around
lids of dust bins, around seats of outdoor privies, spaces under chips
of wood, around stacked materials of any kind, in deserted animal
burrows or rodent holes, and entwined in grape arbors. This spider may
find its way into clothing or shoes and occasionally seeks a spot in a
house to build a web, but it is usually not found indoors. When it does
seek shelter in a building, it is due to cold weather and a need for a
dry shelter. In addition, in the eastern United States, Latrodectus mactans
is associated with littered areas, with dumps of large cities, with
garages, and storage sheds. In arid parts of Arizona, this spider
inhabits almost every crevice in the soil and its nests are found in
cholla cacti and agave plants. (Ferrand, 1988; Kaston, 1953;
Preston-Mafham, 1984; Comstock, 1948; Gertsch, 1979; Shuttlesworth,
1959; Snow, 1970; Smith, 1980; Emerton, 1961; “Black Widow Spider,
http://www.nscu.edu)

The Bug Guide has nice pictures and says that the name, Latrodectus mactans, is a mixture of Latin and Greek for "murderous biting robber".