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Hi Folks,I am new here so forgive me if this question has been asked before.
Do some butterflies emit U.V. or infra red as flowers do ?
I ask because several times watching a butterfly I have seen a bee or hoverfly try to land on it as if it was a flower.

It's not exactly that plants 'emit' UV but that they reflect UV components of the spectrum in a selective way, which the eyes of birds and insects can see. I would not be surprised if butterfly scales show patterns in the UV region, just as plants do, and these will certainly be visible to other insects. I'm afraid I do not have information on any experimental research that may have been done - others on this site may know more.

A lot happens in parts of the spectrum where our eyes do not respond. For example, scorpions fluoresce strongly when illuminated by UV radiation!

Thank you for raising the question and welcome to the forums.

As MikeOxon suggested some butterflies do actually fluoresce under UV light. I know that some Eurema species show this and that some species of Australian Hesperids are more easily identified by examining the male sex brands under UV light.
Here's just one paper on the subject : FLUORESCENCE IN THE COLORS OF CERTIAN
LEPIDOPTERA OBSERVED UNDER ULTRAVIOLET LIGHT http://images.peabody.yale.edu/lepsoc/j ... illips.pdf

I read somewhere that ordinary whites, eg Large and Small, look blue(ish) in the u/v spectrum. It is speculated that butterflies can "see" in the u/v. This blue colour might help mate detection/selection.

Some experiments are called for here.

Jack