Yellow Garden Spider Revisited

I took one look at you ....and my heart stood still--------Rogers & Hart

stabilimentum

On a field trip with the future teachers of Discover Nature Schools we ran into this beauty.  The distinctive zigzag pattern seen vertically through the web is called a stabilimentum. It is common among the Argiope sp. (Ar-gee-O-pee) spiders but is produced by over 80 spider species.  A. aurantia makes an especially thick stabilimentum. It is called a "writing spider" from an old old folk tale that says if you see your name written on its web you are about to die.  So much for the kind and empathetic writing of Charlotte's Web.  No students were lost on this trip.

This is a female Argiope aurantia, the yellow garden spider.  The females are three times larger than the males with a body length of 19-28 mm.  The Araneidae family members all have eight eyes in a distinctive arrangement but with black eyes on a black face they are hard to photograph.  This is a very active spider that crawls all over our hands.  I was finally able to get head shots by gently holding it between soft foam rubber pads.  Her pedipalps are long and narrow compared to a male's which are specialized for the job of transferring sperm.

Male and female - Jay Barnes

The beautiful circular web A. aurantia builds is temporary, as they eat all but the long foundation webbing every night, spinning a new web for the next day. Some sources suggest they may do this to add tiny particles to the webbing which look like food to small insects, drawing them to the web.

The zigzag stabilimentum is especially interesting. It is made of a slightly different webbing which reflects UV light, possibly attracting insects to it. It is important to recall that other species frequently see different light waves. Other biologists believe the stabilimentum is made to strengthen the web, confuse predators, or to warn birds not to fly into the web.

A stabilimentum didn't save this hummingbird that flew into a web in front of one of our cardinal flowers, Lobelia cardinalis.  The closely related Argiope trifasciata spider went into its reflex action of wrapping up its prey (or bycatch in this case).  It is possible however that the hummingbird wasn't an entirely innocent victim.

"Hummingbirds use spider webs as a source of spider's silk in nest construction, being necessary to bind the nest to the tree branch or other substrate and to hold the nest together. Even so, the hummingbird must be careful when removing the pieces of webbing, for it may become entangled and be trapped there. Spider's silk has a tensile strength comparable to steel on a weight basis. In one report, a ruby-throated hummingbird was caught in an active web, and quickly wrapped and encased by the spider, much as an insect might be." Hummingbirdsociety.org

Spider web construction varies with the species and many spiders don't even bother to make one.  The initial strand in web construction of Argiopes is called the "baseline."  It then drops a single line in a "Y" and builds the radials before adding the sticky web.  Most lose stickiness after a day and are eaten by the spider who then, in the ultimate in recycling, uses the ingested silk to reconstruct the web.  Details and diagrams of their techniques are at spiderzrule.com.  When most prey hits the web, the spider rushes out and bites it, killing it before its thrashing allows it to escape.  With some venomous insects like wasps they just carefully wrap it in silk.

Whether you like Latin names or not, the name Argiope aurantia is necessary to confidently identify the species.  Using "binomial nomenclature" creates a universal name recognized in all languages. Between three different authoritative sources it carries the common names of writing spider, corn spider, black and yellow garden spider, zipper spider, banana spider, x spider, corn spider, the yellow and black garden spider, the black and yellow argiope, the golden orb weaver, and yellow argiope.  This impressive list demonstrates the importance of a scientific Latin name.


The story of a female spider eating the male after mating is a familiar one in many species (see black widow blog). The Argiope is different.  The male effectively commits suicide by sex. Spiders transfer their sperm to females using their specialized palps which the male inserts into the female.  In the case Argiopes, they die right after inserting their second palp, their heart stops beating several minutes later.  This gives a whole new meaning to Rogers and Hart's lyric, "...and my heart stood still."

The second palp remains inserted into the female, effectively plugging the opening and preserving the male's genes from contamination from another male. In other words, he makes the ultimate sacrifice to preserve his inheritance.*

The male’s death is also described as an “irreversible seizure” and apparently this takes place to form a kind of “chastity belt” (James 2003*). Once the male Kamikaze has inserted the second palp, he’s stuck, despite what the surrounding males would like. "The other males go berserk, bite into the legs and try to pull him off." Securing himself inside of her also gives the male’s sperm sufficient time to fertilize the eggs.**

Meanwhile the female never gets to enjoy her 1000+ kids.  She makes a round brown egg sac, attaches it to the web and watches over it.  The spiderlings hatch but the newborn spiderlings remain in the sac over winter while she dies.  They will emerge in the spring to spread out into new territory.  I wonder if the thought of raising 1000 kids is what kills her?

"Bug Eric" Eaton's blog
*    See this NIH publication.
**  Comprehensive A. aurantia information with references is at this link.
More photographs in Bugguide.