Sign Challenge #1 Reveal: Spinybacked Spider Egg sac

February 10th, 2013 - 12:25 PM | Filed under Sign Challenges | 2 Comments

This reveal for Sign Challenge #1 is long overdue. Here’s the challenge photo again:

~15mm long | August 23, 2012 | Sebring, FL, USA

~15mm long | August 23, 2012 | Sebring, FL, USA

Commenter Daniel Heald correct guessed it was a spider egg sac. Here’s another angle:

Dorsal view

Dorsal view

When I took the photos, I assumed it was a cocoon. I was curious to see what moth would emerge, so I took it home with me.

After looking through Tracks & Sign of Insects and Other Invertebrates, I realized it was actually an egg sac for a Spinybacked spider (Gasteracantha cancriformis). In fact, I had seen many of those spiders in the area. The egg sac’s yellow silk, dark longitudinal line, and placement on the underside of a leaf all point to this species.

In Spiders of the Carolinas, L. L. Gaddy notes that in over twenty years of fieldwork he’s not seen the egg sac or male of this species. Perhaps I’m just lucky, but I suspect I’m more of a leaf flipper than Gaddy. The egg sacs are placed on the undersides of leaves, which is where I’m always checking for caterpillars.

I was curious to see the spider eggs, so I peeled back a few layers of the silk and found the spiderlings had already hatched. Turns out they stay in the egg sac for weeks before emerging.

Spiderlings revealed

Spiderlings revealed

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Closer look

I had hoped to see the spiderlings grow, but they all died after a few weeks.

References:

Spiders of the Carolinas
by L. L. Gaddy
Tracks & Sign of Insects and Other Invertebrates:
A Guide to North American Species

by Charley Eiseman and Noah Charney

Red Widow with Egg Sac

September 25th, 2012 - 8:59 PM | Filed under Featured Photos | No comments

~15mm long | August 21, 2012 | Tiger Creek Preserve, Babson Park, Fl, USA

While on my way to BugShot 2012, I spent several days exploring parks along the way. My favorite spot was the Nature Conservancy’s Tiger Creek Preserve for the variety of habitats its trails pass through.

Here, I was curious about some some palmetto leaves that had been sealed up. Peeling a layer of leaves away, I found a red widow guarding her egg sac.

Lynx Spider Guarding Egg Sac

July 8th, 2012 - 5:56 PM | Filed under Featured Photos | No comments

~10mm | January 7, 2012 | Tupaciguara, Minas Gerais, Brazil

On the underside of a leaf, an attractive lynx spider guards her egg sac.

Dorsal view