September Spider Sleuthing in the San Juans – Day 8 Araneus diadematus, the Cross Orb weaver


Yesterday my husband was outside working on our deck (without much help from me). The weekend projects can be overwhelming, especially when I’m so easily distracted every time I find a BUG. This one was perfect for my post today!

Female Cross Orb Weaver, Araneus diadematus 09.07.2020

First off, it’s a SHE spider! This fall beauty is a female Cross Orb Weaver, Araneus diadematus. She was hanging out on the side of the house, just under the eave. I had to carefully climb a ladder to get a photo, but it was completely worth the risk.

Female Cross Orb Weaver, Araneus diadematus 09.07.2020

Orb Weavers are in the family Araneidae. These are some of the most beautiful and commonly seen spiders in our area. They weave the classic and typically vertical, orb-shaped web that we often see in our gardens.

March 29, 2013, Photo by Cynthia Brast-Bormann

While Araneus diadematus is not a native species and was introduced from Western and Northern Europe, it has become naturalized here and ranges across North America now. Bugguide.net gives the North American (including Canada) range for A. diadematus as the following localities – “diadematus – BC, WA, OR, MI, OH, PA, ON, NY, QC, RI, MA, NS, NL.”

Male and female specimens have different morphology (size, shape). Female body length can be from 6-20mm and they are fuller and more rounded. Male body length varies from 6-13mm and they are more narrowed in body shape.

Male A. diadematus

Typically, even though they are around in spring, we don’t notice them until later in the fall (like now). Females will be waiting on their web for a wandering male to find them. Males are not usually seen on webs since they are often on the move to find “Miss Right.”

The female A. diadematus will lay her last clutch of eggs in fall before dying, usually timed with our first frost. The eggs will overwinter. The eggs will hatch in springtime when temperatures warm, releasing hundreds of baby spiderlings!

June 13, 2013 – San Juan Island “Orb-Weaver Spiderlings”

I found this interesting poem online about Orb Weavers that I’ll leave you with today. Thanks for stopping by!

Araneus diadematus

Our cradle empty, we shall climb

To a high place, to catch the wind

And fly, strewing gossamer as we go,

Singly, flowing without will, to land

Wherever.

We shall know, by the compass

Blotched in white upon our backs,

Where to spin the spokes, and how

To spire the wheel; with one leg, feel

The trembling.

Approach too fast, and we shall quake,

And blur the whorl with shaking

From the underside, the compass

Pointing down, our legs the eight points

Taking.

At night we eat the orb, conserve

The silk, to spin again by morning,

Indelicately, cramming all

Into open mouths, every spoke

Consuming.

We spin the globes of nurture

After mating, span them so,

With loving claws, adore the

Minor worlds we make, compass

Turning.

Entwined in silk, their spinnerets

Are forming, massed bundles

Of eyes, and legs, and fangs

Entangling. Each of us

Expiring.

Source material. Veronica Godines, Araneus diadematus, http://animaldiversity.ummz.umich.edu. Theodore H. Savory, The Spiders and Allied Orders of the British Isles, London, 1945, pp. 130–131. The common “Garden Spider” has a characteristic “cross” on its back, and is the archetypal orb-weaver. Immatures, already orphans by the time they emerge, go out to seek their fortunes by abseiling more or less at random on air-currents, attached to an anchor point by nothing but a thread of gossamer.

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