A Spider’s Hidden Egg Sac

I’m not sure what made me stop to examine this leaf dangling from a branch. Maybe it was how it was attached or the unusual shape of the dried leaf. Or maybe because there were two of them within 12 inches of each other. Whatever the reason, I’m glad I stopped to investigate.

I pulled on the leaf to look at it closely. At first I offered a gentle tug, influenced by its seemingly dry and brittle form. It would not come away easily from the branch – the thick silken thread much stronger than it appeared. Pulling it lose tugged at the branch with enough force to bow it slightly, less force than the strength of removing a living leaf from the branch but more than how a slight breeze would sway the branch.

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Once in my hand, the weight of the leaf revealed that there was more than meets the eye here. A crumpled leaf on its own would weight half as much as this. It was becoming clear to me that this leaf was not here naturally, nor was its connection to the branch. The leaf was used as a cocoon of some sort, built like a pot sticker Chinese dumpling and housing either an adult insect or insect eggs in the leaf center. Could it be of a silkmoth? A spider? The only way to solve the mystery was to open it, so I gently pulled it apart like I was opening a book. A very tiny leaf book.

At first I only found dark matter within, its texture similar to rotting plant material but it could also be insect parts. I dug further and began finding silk. Finally, nestled in its center was a globe of silk. I carefully cracked it open to reveal dozens – if not hundreds – of tiny spiderlings!

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Ruler in photo below shows millimeters.
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I’m working on identifying these spiders. If you have any idea, please let me know in the comments below.

My thanks to Charley Eiseman, author of Tracks & Sign of Insects and Other Invertebrates, a book that I flip through constantly. There’s no other field guide like it!

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