As I’m in a rush preparing to leave (and Wildlife Photo posts take a while to put up), so let me be lazy and post three tweets sent by the estimable Matthew Cobb, who follows Twi**er. They are all animal-related, so they fit here.
Since I’m not taking readers’ wildlife photos with me, if you send some when I’m gone, they’ll likely be posted almost immediately. But be sure the photos are good!
First, this one. Now the resemblance to a jumping spider is conjectural, but it sure looks like one to me. The question is this: the predators who presumably avoid this butterfly because of the markings must have had some experience encountering jumping spiders (otherwise they wouldn’t learn to avoid them—or have evolved to avoid them). But the predators on butterflies are often birds, and these aren’t attacked by jumping spiders. Your quiz question: if this is indeed an evolved mimetic pattern, what would be the selective pressures that could produce it?
Dressed for Halloween? The markings on the back of this gemmed satyr appear to mimic a jumping spider. Photo by Bryan E. Reynolds. pic.twitter.com/X2aQeoUk8k
— The Xerces Society (@xercessociety) October 24, 2016
Here’s one jumping spider for comparison. The prediction, of course, is that there must be a jumping spider with nasty effects on some butterfly predator living in the same area as the gemmed satyr. According to Wikipedia, the butterfly, (Cyllopsis gemma) is a nymphalid found in the SE US and NE Mexico. 
Now, for a certain case of mimicry, have a look at this photo. Nope, that’s not a bee but a MOTH (note the antennae).
Clear-winged #Moth (Sesiidae) YES! A moth!https://t.co/cFpBaDmgBm #insect #China #Yunnan #mimicry #notabee #bee #entomology pic.twitter.com/W6TVkmSXz1
— John Horstman (@sinobug) October 25, 2016
This is a truly remarkable case of mimicry. As the Flickr page describes:
Clear-winged Moth (Sesiidae). YES! A moth!
I see my fair share of Lepidopteran wasp mimics, but this is the most convincing bee mimic I could imagine.
Pu-er, Yunnan, China
Here’s a screenshot I took from the Flickr picture so you can see the mimicry better:
And finally, some lovely mountain gorillas. What are they saying? (Be sure to put the sound on.)
Happy mountain gorillas singing while feeding on senecio in the high elevation @SavingGorillas @CASHP_GWU @GWMcFarlinLab pic.twitter.com/ibUPXZWnzO
— Jordi Galbany (@jordigalbany) October 19, 2016

Little Anolis lizards, praying mantis, robber flies, and tree frogs come to mind as possible butterfly predators that would not like to tangle with the fangs of a jumping spider.
There are various other possibilities that occur to me too:
1. The spider isn’t dangerous or distasteful but merely difficult to catch and so not worth the investment to attack; this too might benefit a mimic.
2. The mimicry is a false target, encouraging predators to attack the wing, thus letting the butterfly escape.
3. Pareidolia.
I was thinking this as well, along with providing protection from real jumping spiders.
Yeah, there are lots of non-bird predators of butterflies. It might not scare birds, but I bet looking like this scary predator is still better than looking like none of them!
My first reaction to Jerry’s question was that it assumes facts not in evidence, namely that “predators […] avoid this butterfly because of the markings”.
Is there a way to test that? Say by some sort of catch-and-release experiment in which you paint over the markings on some individuals, and then recapture them later to check for differential survival?
The bee mimic seems to be enjoying some tasty bird poop. I wonder what he/she gets from it.
I would guess amino acids, which could be low in a nectar diet.
In which case, probably she.
That jumping spider would be great in a monster movie. And very colorful.
The spiders can hear you… be careful what you say!
https://entomologytoday.org/2016/10/17/jumping-spiders-can-hear-sound-despite-having-no-ears/
Jerry,
What is this nonsense?
http://www.upi.com/Science_News/2016/10/25/Faulty-fossil-record-analysis-plagues-studies-of-evolution-biodiversity/2971477403412/-/web/-1477407368566-trackingCode-+UDMJ88gob23bCmIDnEXcBwAGVgH/LRsJ2gnTUnWFRc=-articleId-375319331-vv-b92c7066-3ad5-447c-9d8f-4088d8aa251b
myles
Why ask Jerry? He isn’t a paleontologist. You can read the abstract here, if that helps:
http://onlinelibrary.wiley.com/doi/10.1111/2041-210X.12666/full
This is an argument about how to correct for one sort of sampling bias in assessing the relative diversity of paleocommunities. The authors find one particular method seriously flawed.
First, bloody amazing that butterfly and moth.
The pressure for the mimetic pattern to my mind could be is to deter birds by diverting any investment to expend energy and time on a non preferred low return choice.
Any terrestrial creatures that would feed on them would be sent packing or freaked by a eat or be eaten dichotomy.
Two bangs for one buck?
Other than that, both butterfly and jumping spider (a ghost meal) are fair game to a predator who cares little for games.