Bob Pyle's _Butterflies of Cascadia_ is a wonderful book and
should be in the reference library of anybody even remotely
interested in the butterflies of the Pacific Northwest, but
it's not a particularly practical field guide.

For the field, I prefer Kenn Kaufman's Focus Guide _Butterflies
of North America_ which uses the same hybrid photo technique
used in his bird guide. It's laid out with multiple species
per page, lots (though not all) variations within a population
and generally easier to navigate.

Then I come home and check my work in Pyle.

--
Mike Patterson
Astoria, OR
celata at pacifier.com

Scale, nature and our infinite capacity to rationalize
http://www.surfbirds.com/blogs/mbalame/archives/003674.html