Evolution has caused a fly to develop perfect-looking reverse images of a spider (or ant) on the tips of its wings, and the fly sits on vegetation with its wings spread on either side so that this false spider is visible. Perhaps it is used to scare away predators, but scientists are still debating how the fly displays its wings and what happens when it does.
http://whyevolutionistrue.wordpress.com/2013/11/05/fly-with-ant-mimic-wings/
http://whyevolutionistrue.wordpress.com/2013/11/05/fly-with-ant-mimic-wings/
Photo credit: Peter Roosenschoon, https://twitter.com/ziyatong/status/397348948857196544/photo/1