Arrowhead Spider
Micranthena saggitta


The Arrowhead Spider is part of a small group of brightly colored arachnids whose leg span is barely 1 inch. The arrow-like structure across its back is actually a thin membrane that supports two hardened horns. The horns are its only defense against predators. The bright zig-zag colors are a disguise to give the impression it is larger than it actually is, as well as to resemble a small flower that might attract a would-be pollinator.

These tiny creatures can be found during the spring, summer, and fall. They lurk around low shrubs at approximately 2 to 3 feet above ground in wooded thickets, wetlands, gardens and marsh areas. It usually sits at the hub of the web waiting for prey to fly into the silky net.

Formally known as Acrosoma spinea, M. sagitta is a member of the class Arachnida, order Araneae, and Family Araneidae. The female is about 1/4 inch body size and the males are smaller. The abdomen is arrow-shaped, narrow in the front and ending behind two large spreading spines. There are also a pair of smaller spines on the front and a spine close to the center on each side. The cephalothorax is light brown or yellowish brown with white edges. The abdomen is white or bright yellow spotted with black above and somewhat darker below with yellow spots and bands of black. The spines are black on the points and red at the base. The legs are the same color as the cephalothorax.

The Arrowhead Spider is absolutely harmless to humans.


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