Salticid mimicry in moths has been scientifically established, at least according to one study: Predator Mimicry: Metalmark Moths Mimic Their Jumping Spider Predators. I've had several respected entomologists speak out in favor of likely Salticid mimicry for Petrophila, along with one amateur collector who expressed similar sentiment confusing this genus with spiders. I'm not quoting names -- I'll leave that to them, should they like.

Regarding the previous comment, I remember learning about a scientific study -- I think it was by someone at UT austin -- comparing the survival of bird-dropping caterpillars to non-bird-dropping caterpillars when exposed to birds and finding clear evidence in favor of bird-dropping mimicry. Done with this topic, off to do other things now...

Please don't take this personally, but I have noticed for a long time the propensity at BugGuide for calling anything that has certain pattern resemblances "mimicry" or "bird-dropping." Mimicry in biology, such as Batesian Mimicry, has demonstrable survival benefit to the mimic species. This is well understood in certain pairs or groups of butterflies. So far as I am aware, nothing like it exists in moths, at least in North America.

In this case is would make as much sense to me to say that the spider is mimicking the moth. But I assure you that, if moth and spider come into contact, the spider will feast on the moth, thus proving that there is absolutely no mimicry value at work. There is simply similar patterning arrived at by more or less random design work achieved through natural selection.

With respect to the vastly overused "bird-dropping" description, which is merely a generalization applied to many moths in many families, I defy anyone to come up with photographs of genuine bird droppings that are bisymmetric in apperance (thus REALLY mimicking a typical organism). I doubt that they exist except at rare, random rates of occurrence. On the other hand I have observed many times in the bushes and mimosa tree near the light trap in my yard, that sparrows, cardinals and catbirds have absolutely no hesitation in devouring every morning napping moths that they find by searching through the foliage. Many of the moth species involved are those sometimes called "bird droppings." There is no survival value (at least with respect to the birds in my yard) in the coloration patterns exhibited by these moths.

I realize that this is a topic that might better be placed in one of the forums, but I rarely post there. If someone wants to move this to a forum to encourage further discussion I have no objection.

Moved from ID Request.