An arrowhead-shaped spider at the center of her web
Mid-July in Pittsburgh, and the woods were full of orb webs. Most of their owners scurried into the foliage when I approached, but this one stayed put in the center of her web, bold as could be: a yellow abdomen shaped like an arrowhead, marked with black, and armed with pointed spines along its edges.
This is Micrathena sagittata, the arrow-shaped orbweaver, a member of the orb-weaving family Araneidae in the order Araneae. The species name sagittata comes from the Latin for arrow, and one glance explains why. The bright, spiny abdomen is typical of the genus Micrathena, whose females come in a startling range of shapes.
Those spines and that bold coloring are a kind of armor and advertisement. The web is a classic orb, built in open spots along woodland trails, and the female waits at its center, where sunlight turns her yellow body into a tiny landmark. Males of the species are much smaller and unremarkable, and they approach a female’s web carefully, mindful that the same jaws that handle prey could handle them too.
Her web was strung between two low branches at eye level, and the morning dew made the silk visible, a map of patience. I crouched beside it and watched her deal with a small fly, wrapping it efficiently before settling back to wait. For a creature with such a dramatic silhouette, she was entirely businesslike. The arrow shape that makes her so easy to find is the same trick that warns birds: a spider this visible is probably not worth the trouble.
