Banded garden spider (Argiope trifasciata, Forskål), Justin, Texas

Report and Photographs Courtesy of Stephen M., 21 July 2007

Editor's Notes by Jerry Cates

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Stephen Wrote:

Hello--I think this is related to the yellow garden spider, not sure though.  It just had hundreds of babies that I saw last night.  I took this photo on 7/1/07 near Justin, Texas.   Thanks, Steve M. [Editor's Note: Justin, Texas, is between Fort Worth and Denton, just west of Interstate 35W]

Editor's Notes:

The banded garden spider (Argiope trifasciata) is found throughout the world, except in Europe, where it is replaced by a similar species, Argiope bruennichi.  The latter species is also found in Asia, North Africa, and in the Middle East.  In North America, Argiope trifasciata is often found in the central and northern U.S. states, and in southern Canada (from the Pacific to the Atlantic coasts, and most parts in between).  

The first taxonomical analysis of this species is attributed to Peter Forsskål.  Today his surname is often spelled with a single 's'.  The major scientific tracts bearing his name were published by Carsten Niebuhr 12 years after Forsskål died, and Niebuhr spelled Forsskål's name in that manner.  Peter Forsskål was born in Finland, but his family moved to Sweden while he was a child. Later, he studied under the brilliant taxonomist Carl Linnaeus, who recommended him to King Frederick V of Denmark for a 1761 expedition to Egypt and the shores of the Red Sea. All but one of the scientists on that expedition died from malaria, and Forsskål was the second in the party to succumb (1763).

Carsten Niebuhr, the lone survivor of the expedition, is thought to have avoided the fate of his fellows by adopting the habits and dress of Middle Eastern natives.  That theory accords with research I carried out during the 1960's (200 years after Forsskål's death) on malaria avoidance strategies used by natives in Southeast Asia.  Malaria is spread by anopheline mosquitoes, among others, which take blood meals from mammals and in the process inject salivary fluids into the feeding site to prevent the host's blood from coagulating.  The host becomes infected by parasites present in the injected fluids.  I was particularly taken by the methods used by certain native tribes who, during the nighttime hours, housed pigs and chickens under their elevated huts. Foraging mosquitoes, which are most abundant at lower elevations, find abundant victims near the surface of the ground and, therefore, have no need to fly higher for a blood meal.

Note that in the enlarged photo above (which Steve sent the next day) this spider is shown to have an extremely pubescent, i.e., hairy, carapace (the hard, flat plate that covers and fuses the head and thorax into a single body section known as the cephalothorax).  The bright white coloration of the head, around the eyes, contrasts with the slightly darker gray of most of the remaining cephalothorax. The two eyes showing in that area are the largest of this spider's eight eyes.  By position, they comprise the posterior median eyes, or PME. See the tufts of hair on what appear as "cheeks" on each side of the spider's face?  These surround two pairs of lateral eyes, which are not visible. The upper eye of each pair is the posterior lateral eye, or PLE, and the lower one is the anterior lateral eye, or ALE. Below the PME, also in the middle of the head, are two small eyes known as anterior median eyes, or AME.

Several important physiological features, beneath the hairy covering on this spider's carapace, are obvious.  First we see a pair of oblique lines that extend from the center of the cephalothorax outward, toward the pedipalps (the small, leg-like appendages on each side of the head). Each of these two lines is a cephalic groove marking where the head fuses to the thorax.  Just behind the point where these grooves meet is a dark spot, in the middle of the thoracic furrow that separates the thorax into right and left halves.  Radial furrows subdivide the thorax as well.

Stephen is an excellent photographer, as this photo shows.  He has subsequently sent additional photos, which are now posted on this website. We should expect to see this comparatively rare species in greater numbers than usual this year, owing to all the rainfall we've had.  Some specimens may develop abdomens measuring an inch or more in length, rivaling the size of the yellow garden spider (Argiope aurantia). High rainfall levels have set the stage for large numbers of flying insects, like crickets and grasshoppers, to emerge during the summer and early fall months.  They will then feed these spiders in such bounty that they will likely become quite large. 

Many thanks to Stephen for these excellent photos!!!