UV is the chief culprit. If you can use LEDs they give off relatively little UV whereas fluorescent tubes give off a lot. 

-----Original Message-----
From: Entomological Collections Network Listserve [mailto:[log in to unmask]] On Behalf Of [log in to unmask]
Sent: Tuesday, December 10, 2013 1:11 PM
To: [log in to unmask]
Subject: Re: Butterflies on Display -- light levels

Is it UV that degrades the color? If they are under glass maybe the protective glass used to protect art prints might also help?
Just and idea, maybe tried already.


> Lower light levels may slow fading, but it will happen with brown's 
> and green's fading first.  Reds/oranges and yellows appear more stable 
> and less subject to fading, as are the blacks.  It also seems that 
> moths fade quicker than butterflies.
> Richard L. Brown
> Mississippi Entomological Museum
> Box 9775
> Mississippi State, MS 39762
> email:  [log in to unmask]
> PH: 662-325-2990
>>>> Christopher Marshall <[log in to unmask]> 12/10/2013
>>>> 2:22 PM >>>
> Hi all,
> I've recently been asked about light levels for butterfly specimens being
> put on display in a public museum space.   I've been asked if there is an
> 'appropriate' light level that will not rapidly fade the specimen.  
> Has anyone in the museum display arena done a study or published 
> recommendations for light levels that are appropriate.  My first 
> instinct was to have lights that only come on when a viewer is in 
> front of the exhibit or pushes a button.... so that the light was only 
> intermittent -- but the exhibit director is not sure they can do that 
> and so has asked if there is a lumen level that might be acceptable.
> I quickly searched the ECN archives, but didn't find anything -- but 
> if this thread was already addressed can you post a link?
> thanks,
> Chris
> Christopher Marshall
> Curator & Collections Manager
> Oregon State Arthropod Collection
> Zoology - Oregon State University
> Corvallis OR, 97331-2914
> [log in to unmask]

James B. Whitfield
Department of Entomology
320 Morrill Hall
505 S. Goodwin Avenue
University of Illinois
Urbana, IL 61801