This attractive set of Laotian Butterflies was designed by by M. Leguay (20 k.), S. Rodboon (others) and engraved by J. Pheulpin (10k., 25k.) R. Cami (20k., 40k.) Recess. Released February 25, 1965. A nice addition to a Butterlfies on Stamps collection.
For superb image gallery of the Butterflies of Laos, see: http://www.pbase.com/bfmom/lao_butterflies&page=all
Collectors of Butterflies on Stamps would be well advised to join the Biology Unit of the American Topical Association: http://www.biophilately.org/