Butterflies of the Pacific Northwest - Robert Michael Pyle & Caitlin C. LaBar, 2018
Butterflies of the Sinlahekin Wildlife Area - Caitlin C. LaBar, 2017
Pocket Guide to the Butterflies of Washington - Caitlin C. LaBar, 2017
The Butterflies of Cascadia - Robert Michael Pyle, 2002 (out of print)
Butterflies of British Columbia: including Western Alberta, Southern Yukon, Alaska Panhandle, Washington, Northern Oregon, Northern Idaho, Northwestern Montana - Crispin S. Guppy & Jon H. Shepard, 2001
Life Histories of Cascadia Butterflies - David G. James and David Nunnallee, 2011
Butterflies of North America - Jim P. Brock & Ken Kaufman, 2006
Handbook for Butterfly Watchers - Robert Michael Pyle, 1988 (out of print)
Caterpillars in the Field and Garden - T. J. Allen, J. P. Brock, J. Glassberg, 2005
A Catalogue of the Butterflies of the United States and Canada - Jonathon P. Pelham, 2008
The Wild Silk Moths of North America - P. M. Tuskes, J. P. Tuttle, M. M. Collins, 1996 (out of print)
Basic Techniques for Observing and Studying Moths & Butterflies - William D. Winter Jr., 2000
INSECTS (general guides)
Pacific Northwest Insects - Merrill A. Peterson, 2018
Insects of the Pacific Northwest - Peter Haggard & Judy Haggard, 2006
Insects of North America - Eric R. Eaton & Kenn Kaufman, 2007
Bugs of Washington and Oregon - John Acorn & Ian Sheldon, 2001
A Field Guide to the Tiger Beetles of the United States and Canada - David L. Pearson, C. Barry Knisley and Charles J. Kazilek, 2006 1st ed. (there have been problems with the 2nd ed. missing color plates, be cautious if purchasing it)
Grasshoppers, Katydids, and Crickets of the United States - J. L. Capinera, R. D. Scott, T. J. Walker
A Field Guide to the Tiger Beetles of the United States and Canada - David L. Pearson, C. Barry Knisley, Charles J. Kazilek, 2004
Dragonflies and Damselflies of the West - Dennis Paulson, 2009
Plants of Southern Interior British Columbia and the Inland Northwest - Robert Parish, 1999 (out of print)
Sagebrush Country: a wildflower sanctuary - Ronald J. Taylor, 1992 (out of print but can usually find reasonably-priced copies)
Plants of Western Oregon, Washington, and British Columbia - Eugene N. Kozloff, 2005
Trees and Shrubs of the Pacific Northwest - Mark Turner & Ellen Kuhlmann, 2014