Argiope Trifasciata Spider--Doggone Buggone at 2018 Start

Tch! On the last day of 2017, I took pix and video of an argiope trifasciata spider. (For background, read "Argiope Trifasciata Spider--Final Bug Spotting of 2017".) The next morning, I went to the web; she was nowhere to be found. Over the next few days, we’d peered into the plant—no sign of the spider, nor indicators of web disturbances, nor egg sac.

I’m guessing that the spider did not undergo a "normal" life cycle. From BugwoodWiki's “Banded Garden Spider”:

The overwintering stage is the eggs, which are protected within an egg sac attached to vegetation. Upon hatch in spring the spiderlings disperse, … Adult males begin to appear in late July and females shortly afterwards. The males wander while the females remain within a web. Mating occurs in the latter half of the summer and females produce egg sacs, … Freezing temperatures kill off all remaining spiders at the end of the season and they have a one year life cycle.

I’m going out on a limb here. The case for the spider to not having been there in the summer and fall is lack of any egg sac since having spotted her on New Year’s Eve. I propose that the weather, fast approaching freezing, resulted in lack of prey or male, possibly (probably?) influencing her to abandon her web.

I gleaned the following temperature info from December 30 through January 3 results, using Weatherunderground's Wundermap for my area:

December 30 temps—high in low 60s at noon, temp 49ish around 8 PM when we spotted the spider.
December 31 temps—40 at AM start, 37ish around 8 AM when I took pix of the spider, gradual temp drops.
January 1 temps—mid-20s at AM start, less than 30 throughout the entire day and evening.
January 2 temps—lower than 30 throughout the entire day and evening.
January 3 temps—20s at AM start, climbing to 30s around 9 AM, climbing near 60s around 4 PM, then cooling down as evening progresses.

I speculate that the spider constructed the web during reasonable temperature, before the freezing temperature set in and that lasted a few days. During the freeze, prey maybe didn't approach the web (unwittingly or not); thus, no food for the spider. No male argiope trifasciata spider approached the web for mating; thus, no need for the female to create an egg sac.

A few successive days of looking at the plant and noting the intact web, I sensed the female abandoned the web. I ruled out the possibility of a predator making a meal of the spider. I think a struggle would have resulted in the web being wrecked.

One other oddity: The orb web did not have a stabilimentum (elaborate web decoration) as I've noticed in several other images of female argiope trifasciata spider webs. The lack of stabilimentum might have indicated the stoppage or interruption of the spider's "housekeeping setup" process. Read more about stabilimenta.

Curious about doing your own weather timeframe lookup? Start at https://www.wunderground.com/wundermap.

1. Confirm or click All Layers > Weather Stations > Temperature / Wind.
2. At the search field, enter your city of interest, then enlarge the view to the scale you want.
3. Scroll to the area of interest. (The results might be slow to arrive.)
4. Click a number. When the inset window opens, click Visit local weather page for [your locale].
5. At the new window, scroll down to the weather history options. The first option is interval, the default being daily. You can set for larger intervals or customize for date range. View graph or table.
6. The newer window has an enlargeable inset map with additional station numbers you can click and find similar information.

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.