Bolas Spider (Mastophora cornigera)
Detailing the identifying qualities of the Bolas Spider, including physical features and territorial reach.
Updated: 2/8/2018; Authored By Staff Writer; Content ©www.InsectIdentification.org
The Bolas Spider's abdomen helps it lure prey into its delicate, hanging lines of silk, each strand tipped with a weighty ball.
The Bolas Spider is not a web spinner. Instead, it casts lines of silk strands with a heavy globule at the end called a bola. It swings the bola when prey is within range. This species ensnares moths that fly too closely to it. It is believed to be able to produce a chemical from its abdominal protuberances that mimics the pheromone, or smell, of female moths. When male moths come seeking to mate, they are caught by the lines of silk.
Bolas Spiders are brown with an irregularly shaped abdomen. Two bumps on it look more like deformed outgrowths. A whitish marbling over the abdomen looks like a chalky residue. Males remain quite small, but females molt multiple times, growing to be 5 or 6 times larger than males. Fertilized eggs are laid in a hard, round sac and spiderlings hatch in June.
The Bolas Spider can be found in a variety of habitats ranging from gardens and meadows to shrubby areas and woodlands. They are more common in southeastern North America but have been seen westward all the way to the southern parts of California.