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Painted Lady - Vanessa cardui

Painted Lady - Vanessa cardui
Wilson, Brevard County, Florida, USA
October 31, 2014
This is a Painted Lady, but I placed it on the ID Request page because I'd like to know the reason that these guys have hairy eyeballs.
My best guess is that the hairs act as blinders that better differentiate what each eyelet sees and that that somehow helps to form a better image in their tiny insect brains. Just sayin', but if there is an actual scientific explanation, I'd be grateful if you could point me to it.
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Painted Lady - Vanessa cardui Painted Lady - Vanessa cardui

Moved from Painted Lady.

[added message: 4:08PM] I see you beat me to it Cliff - just barely. It dawned on me that I commented without moving, and it might be good to save this one.

Explanation and image for archive record in BG.
Moved from ID Request.

I'm not sure if it has actually ever been studied,
at least not as to why. Though there could be information I've never seen on the subject. However, the presence of hairs has been noticed, and is one of the traits that was used by early butterfly taxonomists when grouping species (and genera) of butterflies. Hairy eyes is a characteristic of the tribe Nymphalini. However, there are other groups where one species might have hairy eyes, and nother closely related not.

It seems to be a trait (in butterflies) that is more common in species from northern latitudes and cooler higher elevations; however, it correlation is not perfect. Some tropical butterflies have distinct hairs on their eyes, while many from cold climates do not.

Having something to do with quality of vision makes some sense, but I don't know if it is a real explanation (??). I've wondered if perhaps another explanation might be that they act as something akin to sunglasses, blocking some of the light coming in at an anble to the lenses under high UV (or other wavelength) conditions. Of course that could be complimentary to your explanation.

I'm just guessing though.

Hairy Eyeballs
Thanks David!
Humm... Kinda like baseball hats for BFs.
I understand that there are also other insects that have the same feature (some of the bees), so perhaps there's been some research on bee's eyes that may also bee applicable to the Nymphalini tribe.

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