Monday, October 30, 2017

Argiope Aurantia Spider--Part 2, Post-Friday 13th Observations

My previous article "Argiope Aurantia Spider--Part 1, Friday 13th Visitor" is an introduction to a spider that we spotted in our photinias around 4 PM on Friday 13th. It had alien-face features on its back, with its large orb web and zigzag design. Took pix at varying angles for capturing features and web.

The next day around the same time, the scenery changed. The orb web was gone, seemingly replaced by a bridge-like structure between two taller plants. The spider was nowhere in sight. We thought maybe it might repair the web. From "Black-and-Yellow Argiope Spider", "Black-and-yellow argiope spiders often construct and repair their webs after dark". We decided to visit the area the next few days to observe additional changes. By the 16th (Monday), we took new pictures, trying to replicate some of the framings.

Between the 13th and 16th, I had researched the argiope aurantia spider. One unusual feature is its forming of one or more egg sacs, which occurs after orb web construction. We reviewed pix from the 13th. Aha! An egg sac already there! So, the spider had already set up a nursery even before we'd spotted her and orb web on the 13th.


Unfortunate that we have only one pic from 13th with egg sac. However, we have several pix from 16th that show it. See composite for its relative location.


They also show the different web structure and lack of spider. (On the 13th, orb web.)


On the 16th, the bridge-like web spanned two taller plants, as though a possible dismantling of the orb web. As really amateur observers, we speculated that the spider might have wrecked the orb web deliberately and departed.


Maybe the web clump centered between the taller plants might distract predators' eyes away from the egg sac, positioned at the leftside plant.

Friday 27th morning, we noticed that the bridge-like web was no more, speculating that the previous night's winds overcame it. Oh, well. In any case, the egg sac remains! Bug Eric's article "Spider Sunday: Black and Yellow Argiope" provides information about sequence of events about egg sac(s).
Once mated, a female produces one or more egg sacs, each about the size of a large marble, and covered in tough, papery silk. Inside are 300-1,400 eggs. The eggs hatch in late autumn or early winter, but the spiderlings do not exit the egg sac. Instead, they go into diapauses, a dormant state with lowered metabolism. They emerge the following spring and reach adulthood by late summer. Various parasites and predators can take their toll on the egg sacs and spiderlings, however.
One video that shows an egg-sac creation is "Argiope Aurantia Making Egg Sac Complete (Time Lapse 6500%)". The video owner's description mentions "8 hours of video compressed to around 7 minutes". Exhausting, yet fascinating! A related video "Garden Spider and her egg sac" shows the spider working on her egg sac in the garden, something we ourselves missed seeing.

Speaking of video, I pondered over citing videos in my previous argiope aurantia spider article "Argiope Aurantia Spider--Part 1, Friday 13th Visitor". I decided to save video links for this article (Part 2).

For short but succinct video info about the spider, view "Black and Yellow Argiope Spider Documentary.m4v".

Take a closer look at argiope aurantia spider web-building:
  • "Argiope aurantia "Writing Spider" builds web."
    ("An hour and twenty minutes of the work of an Argiope Aurantia spider building its web is compressed to only three minutes ten seconds in this back-yard video."
    This video contains additional textual commentary.
  • "Argiope Aurantia Making Web Close-up HD"
    ("Notice how the Argiooe [sic] aurantia spider uses each leg to measure out the threads. Also notice how she uses her third pair of legs to cut the scaffolding thread!")
    This video show excellent views of spider's underside pattern (ventral view) as it weaves the web. Note the underside pattern we captured in our own pic.

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