Spined Micrathena

Sara made reference in last month’s blog about those pesky ninja spiderwebs that seem to spring up at face level every time you turn around in the woods.  Tell me this hasn’t been you:  walking along, minding your own business, then suddenly finding yourself shrouded in an invisible net of sticky strands struggling desperately to get free.   Well, it didn’t take many mouthfuls of silk nor rowdy performances of everybody’s favorite “Aaah!!! There’s a Spider on My Nose” dance before I employed a long and (what I hoped to be) menacing spiderweb-saber stick to accompany me on all my voyages out onto the park trails.  But, I soon began to wonder, who are these creatures that go to so much trouble to build such ornate architecture, only to have it destroyed by anything larger than a fly that chances to blunder through?  It was then that I learned of the spined micrathena.

This spider is extremely common in our North Carolina forests.  Many of the orb webs you encounter will belong to these spiders.  The engineering involved in the construction of the webs is incredibly intricate, and the process nothing short of remarkable.   Learn more here:  How Spiders Work.  Although you may experience some guilt in the destruction (whether it be intentional or accidental) of their homes, it may provide some consolation to know that the spined micrathena can complete a new web in about one hour, and routinely rebuild their webs daily.  Or, at least such is the case for the females; male micrathena do not build webs.

Micrathena are easy to identify.  The female spined micrathena is small, less than half an inch from end to end, and has ten long spines poking out from its large triangular abdomen.  Its coloring is mostly white with black spots.  The male is similar, but about half the size of the female, and has fewer spines.   Also common in the forest is the related arrow-shaped micrathena.  Its coloring is red and yellow, and two black spines on either side of its abdomen give it an arrow-like shape. Though the spines of a micrathena might appear threatening, you have nothing to fear unless you are a gnat, fly or mosquito.  Micrathena are perfectly harmless to humans.

Alas, it won’t be for but another month or two longer that you will have to fear the encounter with a micrathena web, for the spider’s lifecycle is almost complete.  We are nearing the end of mating season, and the micrathena have begun laying their eggs.   Though this year’s micrathena will soon die away, their eggs will remain in silk sacks through the winter, and plenty of baby micrathena promise to emerge next spring.

- Arco Williams, fall intern 2012