The spider genus Micrathena contains more than hundred species, most of them Neotropical woodland orb-weavers. Only three species occur in the eastern United States: females of M. gracilis (the Spined Micrathena) have five pairs of conical tubercles on the abdomen, female M. mitrata have two short posterior pairs, and female M. sagittata (the Arrow-shaped Micrathena) have three pairs. Micrathena sagittata is found in the eastern United States and throughout Central America. It is a striking spider with a distinctive arrow-shaped abdomen which is largely yellow, with black depressions above and variable red and black patterning below.
Males are up to 5 millimetres (0.20 in) in length (excluding legs), but females are much larger at around 9 millimetres (0.35 in). The males lack spines. They leave a hole in the center of their web to assist in motion. The photos on this page are of the Spined Micrathena and the Arrow Shaped Micrathena.
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Spined Micrathena (M. gracilis)
Arrow Shaped Micrathena (M. sagittata)