One of the spider's virtues is that it loves to eat flies. However, not all spiders catch flies in their webs.
The jumping spider stalks its prey until, like a tiny tiger, it is close enough to pounce. Rather than defining its territory with a web, the jumping spider takes its territory with it, in a manner of speaking. Wherever the jumping spider is becomes its territory. When one jumping spider encounters another, they wave their legs at each other, warning each other to back off. Herein lies the tale of how one species of fruit fly is able to outsmart the spider. Unlike most fruit flies, this particular species has stripes on its wings. When it waves its wings over its head, it looks something like a jumping spider declaring its territory. When stalked by a jumping spider, the fly is able to convince the spider that it's another jumping spider protecting its territory.
Researchers have discovered why this trick works even though the fly doesn't look much like a spider. The spider's response to the pattern is pre-wired into its brain and is triggered by certain cells in its eyes. These cells are only activated by a display of the pattern. The spider automatically reacts to the pattern. All the fly has to do is fake the pattern and it's safe!
The fruit fly's strategy requires a sophisticated knowledge of the jumping spider's nervous system as well as its behavior. It's safe to say that no fruit fly was able to create this strategy. It could have been authored only by the God who created them both.