Ruary asked: "So why do the touareg (nomadic arabs) wear black?" in response to a comment about white beekeeping suits being generally cooler.

We're getting a bit afield from bees but the short answer is cultural, not thermodynamic.
1.  The tagelmust (men's turban) and alesho (veil for either sex) is indigo, not black.  The sources I've found simply indicate a cultural preference for that color.
2.  The darkness of the dye is an indicator of wealth.  (Because of the lack of water, dyeing involved labor-intensive pounding of the dry dye into the cloth, not the usual saturation method.)
3.  There may be a religious connection since, according to some anthropologists, the wearers believe that the indigo color is a key part of the garments ability to ward off evil spirits.

I'll also note that 19th century pictures (taken during the French invasion) show as many white garments as dark.
 
To the extent that thermodynamics does play in beekeeper suits, remember that the touareg live in an extremely arid environment.  Any reflective power of the cloth is far outweighed by the trapping of moist air (cooled by your own perspiration) near your body.  Loose clothing, regardless of color, will keep you cool.  And even the "moist" air inside the clothing is comparatively dry, minimizing the cloth's ability to transfer any blackbody radiative heat that it has absorbed.
 
I, on the other hand, keep bees in an environment of summer humidity >90%.  Sweat does little for me unless accompanied by a stiff breeze.  The very moist air inside my suit transfers heat well so the blackbody effects of cloth color become more relevant in my environment.
 
Regardless, I firmly believe that the best reason to avoid dark material is evolutionary.  The predators of bees have predominantly been dark colored and furry.  Repeated studies have shown that bees react more aggressively to those materials.  Our suits are as far from dark and furry as we can make them in order to avoid triggering those instinctual responses.  That doesn't necessarily mean white but light is almost certainly better.
 
And to answer an earlier comment, memory has nothing to do with it.  Repeated studies across multiple species have shown fear and/or stress reactions to predator characteristics even among prey species members who had no personal exposure to the predator.  One study I read not long ago (apologies but I can't remember the cite) documented reactions despite multiple generations of freedom from the predator exposure.
 
As to the "red = black to a bee" comments, well, maybe.  If the only light being reflected from the red jacket is the same red wavelength that we can see, it is true that bees can't see those lower frequencies and it would appear black, the same way that an infrared light source appears invisible to us.  If, however, the material also strongly reflects ultraviolet, it might appear quite light and bright to a bee.  The exact material, dye and texture all play a part.  Short of looking through a UV camera, I don't know an easy way to know what your suit really looks like to a bee.

Mike Rossander
www.rossander.org/infosec


      

             ***********************************************
The BEE-L mailing list is powered by L-Soft's renowned
LISTSERV(R) list management software.  For more information, go to:
http://www.lsoft.com/LISTSERV-powered.html

Access BEE-L directly at:
http://community.lsoft.com/scripts/wa-LSOFTDONATIONS.exe?A0=BEE-L