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Western spotted orbweaver Female (Neoscona oaxacensis) Photographs Taken by Sarah M, San Antonio, Texas, 15 June 2007 Edited by Jerry Cates
Sarah Wrote: Mr. Cates, Good afternoon! I am unsure what type of spider this is, but am guessing a yellow and black garden spider based on what I have found online today. Could you please confirm? I want to make sure it is not a poisonous variety, since I have four children that walk by the area frequently. Feel free to use the picture if it will be helpful in any way! Thanks, Sarah M., San Antonio, Texas Editor's Notes: The photo below is of the female's ventral body. Note that the sternum is pale yellow, with darker coxae (the attachments for each leg) at each side. In the center of the ventral abdomen is a square-shaped set of markings common to most species in the genus Neoscona. The square appears, in this species, as a black cross, with a staff and crossmember, the lower portion of the staff being broader than its upper portion. The cross divides the square into four sections, each of which, except for the black cross itself, is white or pale yellow. Posterior to this mark is an orange-colored square enclosing the spider's complex of spinnerets.
"Black and yellow garden spider", the spider's name that Sara mentioned, is an alias for the yellow garden spider (Argiope aurantia). That species is also known by other names, including the black and yellow writing spider. Arachnologists use standardized common names for specific organisms, and follow strict rules for arthropod taxonomomy. While I've not been scrupulous in following those rules in the past, my present intention is to adhere to the scientifically-recognized common names for the spiders posted on bugsinthenews (if you see a mistake, please contact me at jcates@austin.rr.com to let me know). Sarah's spider is not a yellow garden spider, but is another species, from another genus, whose common name is the western spotted orbweaver (Neoscona oaxacensis). This spider can get fairly large, but typically remains smaller than Argiope aurantia. Like other orbweavers, it is extremely beneficial, as it manages to keep populations of flying insects in check. Its bite is painful, and can produce a wound that smarts and produces localized swelling for several days, but is--in general--otherwise inconsequential. Note: Any spider bite that produces a deep wound should be examined by a physician.
The female has a large, globular abdomen and diminutive pedipalps (the short appendages in front of the spider's mouth, which are easily seen in the photo above). The markings on the dorsal abdomen are definitive for this species. Compare the coloration of this specimen to that of a spider of the same species photographed in Dripping Springs, Texas (shown below on the right). The differences in the dorsal markings are considerable, yet numerous similarities can be seen, too. Are these the same species, but different tribes? Or are they members of two distinct species?
Many thanks to Sarah for the photos she sent in. As good a photographer as she will surely send additional photos of other spiders before too long (hint, hint, Sarah...) ---------------------------------------------- We are investigating the risk of secondary infections that may occur as a result of bites from this and other, otherwise harmless spiders whose venom is known to pose little or no danger to humans. In the process, we are collecting information on experiences persons have had with such spider bites. Please contact us about your personal experiences, if you have been bitten by this or any other spider, including jumping spiders and garden spiders (the bites of which typically produce a transitory inflammation, but resolve within a few days without medical attention), whether recently or in the past thirty years, anywhere in the world. For example, the bite of a species of garden spider, the golden orb spider of Australia [Nephila edulis] typically is unremarkable, but on occasion produces medically significant secondary infections; the frequency and nature of bites experienced from that species of spider is also a part of this study. The object of this study is to collect data that might relate to a mysterious series of spider-related infections, involving a special pathogen, that took place in the United States and in Australia between 1977 and 2006. Although only fifteen such infections were reported to medical establishments, seven appear to be associated with spider bites. Some authorities suggest that the number of actual infections of this type that occurred in the U.S. and Australia during the past thirty years is much larger, but that they have been underreported. Underreporting of specific kinds of infections can occur, either because the persons infected chose not to seek medical assistance, or the medical establishments misdiagnosed the infections as being caused by other infectious agents. We are seeking to establish an estimate of the number of human spider bites that occur each year by these and similar spiders, whether the bite resulted in injury to the human or not. Next, we hope to establish the number of instances where the bite (1) became inflamed and/or infected, then resolved without medical intervention, or (2) infected, ulcerated, or led to a generalized sickness, and required medical intervention. ---------------------------------------------- Back to: Texas Spiders Back to: Bugsinthenews |
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