Western spotted orbweaver Female (Neoscona oaxacensis)

Photographs Taken by Sarah M, San Antonio, Texas, 15 June 2007

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?

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