Red Spotted Ant Mimic Spider

Members of the genus Castianeira are considered mimics of large ants, such as carpenter ants, and mutillid wasps, which are known as “velvet ants.” These spiders walk about slowly the way ants do and then only move fast when disturbed.  Castianeira descripta, the red spotted ant mimic spider only walks with six legs, like an ant. As they walk, their front two legs are raised in the air and quiver quickly up and down like antennae. They also quiver them briefly after they stop walking. They do this to emulate ant antennae and  spiders that imitate ant antennae frequently have conspicuous front legs. It is a characteristic of C. descripta that her front four legs are somewhat transparent and not jet black like the rest of her. Looking at them makes you think more of a wasp than an ant, and perhaps that transparency might also be mimicking wasp wings. Wasps often give their wings a quick shimmy upon landing, just as C. descripta gives her transparent front two legs a quick shimmy when she stops moving. 


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