Butterflies and moths of North America:

Butterflies of North America:
http://www.npwrc.usgs.gov/resource/distr...
Butterflies of Southeastern Arizona:
http://nitro.biosci.arizona.edu/zeeb/butterflies...
The moths of Southeastern Arizona:
http://nitro.biosci.arizona.edu/zeeb/butterflies...
Butterflies of Northern Mexico and Sonora:
http://nitro.biosci.arizona.edu/zeeb/butterflies...
Web Images of North American Moth Species:
http://www.furman.edu/~snyder/leplist/

Butterflies and moths of other countries:

Captain's European Butterfly Guide:
http://www.captain.ndirect.co.uk/index.htm
Catalogue of the Lepidoptera of the French Antilles (also available in French):
http://www.jouy.inra.fr/papillon/indexeng.htm
The butterflies in the suburbs of Tokyo (also available in Japanese):
http://www.asahi-net.or.jp/~nz8k-tmy/another...
Database Butterflies of Poland (also available in Polish ):
http://motyle.biol.uni.torun.pl/eng/amotyle.htm

Particular species:

Lepidoptera (family trees):
http://phylogeny.arizona.edu/tree/eukaryotes/animals...
Parnassius of the world:
http://www.hultsfred.se/users/t/tgorw...
Sphingidae of the Western Palearctic:
http://hometown.aol.com/tpittaway...

Others:

Children's Butterfly Site:
http://www.mesc.usgs.gov/butterfly/butterfly.html
Coal Creek butterfly Garden:
http://bvsd.k12.co.us/schools/coalc...

Articles about butterfly gardening:
http://rs306.ccs.bbk.ac.uk/flora/buttart.htm
List of butterfly plants:
http://www.audubon.org/chapter/fl...

Butterfly photos by Philip Greenspun:
http://photo.net/photo/butterflies/
Chuck's butterfly page:
http://www.aa6g.org/lepidoptera.html
The beautiful world of butterflies: Butterfly photographs (also available in Italian):
http://www.thais.it/entomologia/default_uk.htm

Tufts Butterfly Thermodynamics project:
http://www.tufts.edu/as/geo/bm/butterfly.html

INSECTS of RUSSIA:
http://www.osipov.org/