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Sign Challenge #1 Reveal: Spinybacked Spider Egg sac

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. read more

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Thread-legged Bug with Spider Prey

30mm long | December 30, 2011 | Quirinópolis, Goiás, Brazil

This thread-legged bug appears to be hanging in mid-air, but in fact it has delicately balanced itself on a spider web. Its beak holds a small spider that it must have just plucked from the center of the web.

Some thread-legged specialize in spiders, and I wonder if this might be one of them. Some are even known to lure the spider by plucking at the web like captured prey might.

Another view

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Gold-spotted Orb Weaver

18mm | January 20, 2011 | Armonia Nature Preserve, Limon Province, Costa Rica

This large orb weaver was hanging out in the understory. I believe this might be Eriophora nephiloides. Most online photos for the species show a brighter yellower abdomen. It appears to be quite variable. Here’s a photo of one similar to mine (along with what’s pictured at wikipedia).

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Golden Silk Spiders, Mating

January 19, 2011 | Armonia Nature Preserve, Limon Province, Costa Rica

When I first spotted this female Nephila clavipes, she was positioned rather low in her web. Her background was cluttered and shaded. I prodded her a few times, and as I’d hoped, she retreated to a higher position in her web where I thought I might be able to get a more pleasing background.

Unexpectedly, her quick movements drew the attention of a male that was also hanging out in her vicinity. I’ve read that males prefer to mate when the female is preoccupied with a meal (so they’re less likely to become a meal themselves). Perhaps he mistook her quick retreat as movement toward prey. At any rate, he wasted no time approaching her and getting into a mating position. read more

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Golden Silk Orbweaver

January 18, 2011 | Gandoca-Manzanillo NWR, Limon Province, Costa Rica

I’ve never quite been happy with any of the photos I’ve taken of this species, Nephila clavipes. This photo is no exception. I do like that it captures the gold color of the web, and that at least a few of the leg tufts are in focus.

It’s a shame the spider lost a leg somewhere along the way. The missing leg distracts me every time I look at her.

These spiders really are quite large. This one measured around 30mm, 70mm if you throw in the legs.

See if you can spot the little fly that’s perched on her abdomen. read more

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Immature Argiope

January 18, 2011 | Gandoca-Manzanillo NWR, Limon Province, Costa Rica

Closeup crop

Argiope spiders are easy to recognize. They sit head down in the center of their webs with their legs paired up. They don’t even bother to hide themselves during the day. They are among a relatively small number of orb weavers that add a decoration to their web, called a stabilimentum.

The form of the stabilimentum may change as the spider grows. Young spiders like this one may create a dense circular pattern as shown here. Older spiders are more likely to create sparser designs in various shapes. read more

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Alpaida species?

5mm | January 17, 2011 | Cahuita National Park, Limon Province, Costa Rica

One of my books (below) has a picture of a very similar looking spider identified as a spiny flag spider, Alpaida cornuta, also from Costa Rica. I wasn’t able to find anything online though using either the common name or the scientific name. The World Spider Catalog doesn’t seem to recognize that name at all, but I saw two species there from Costa Rica, A. bicornuta and A. championi. Perhaps this is one of those.

Here’s a similar looking unidentified Alpaida from Ecuador, so I think the genus is probably correct. read more

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Silver Argiope with Wasp Prey

January 27, 2010 | Caraça Natural Park, Minas Gerais, Brazil

This spider was on an exposed ridge overlooking the sanctuary. She appears to have caught a nice sized wasp.

This species often creates an X-shaped design (stabilimentum) in their web, and you can just see a hint of one extending to the lower right.

The common name Silver Argiope is consistent with the scientific name (argentata = silvery). Even the common name in Portuguese, Aranha-de-prata, translates as Silver Spider. It is indeed silvery.

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Orb Weaver

January 27, 2010 | Caraça Natural Park, Minas Gerais, Brazil

This orb weaver was safely tucked away inside a leafy retreat.

The general shape puts me in mind of Acanthepeira species here in the US. There is at least one species, A. labidura, in Brazil. I couldn’t find any information on it though.

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