Arrowhead Spider

 

This gorgeous spider is called the Arrow-shaped Micrathena (Micrathena sagittata). Relatively small in size, but remarkable in their coloring. They reach about 3/8 inch in length. The females have an arrow-shaped abdomen from whence they get their name, this abdomen has three pairs of pointed tuberacles, with the rear pair being large and spreading, it is this spreading that gives them a triangular or arrowhead shape.The tuberacles are tipped with black and are red at the base. The center of the abdomen is bright yellow in color, the cephalothorax is reddish in color with a light yellow stripe down the side.  The males are smaller and lack the tuberacles. 

These spiders can be found throughout the Eastern United States and South America. They are also in Texas and Nebraska. Females build webs near timbered areas, and sometimes gardens. The web will have a hole in the center and a stabilimentum located at the top of the center hole. It is presumed that the hole is to allow for freedom of movement, and that the stabilimentum aids in strengthening the web. The bright color of this spider probably helps protect it from predation from birds, lizards, and most insects. Although, mud daubers are known to prey upon this spider. They paralyze it, and carry it back to their mud nests as a provision to their offspring. Despite their bright coloring they are completely harmless to humans, as are all spiders within this genus. This is an amazingly beautiful spider, and I feel very fortunate to have found one.