Micrathena gracilis is a spider in the family Araneidae (orb-weavers), commonly known as the Spined Micrathena. This spider spins a moderately large (may be an inch or more across), very tightly coiled web, often in wooded or brushy areas. It is completely harmless to humans.

The only web-building members of the species are the females. They exhibit a bulbous abdomen with a total of ten spines. Males exhibit a fair amount of sexual amorphism. They tend to be around only half the size of the females. Also, they have fewer spines, a flatter abdomen, and a slighter lighter tone. Although males can produce silk, they mostly use it in the mating ritual, which frequently also proves fatal.

Micrathena gracilis hatches in the spring, the image of an adult. After the summer's growth, the female lays eggs in a sack. These remain relatively dormant through the winter months. The general life span is one year in length.