Xerces Society's 100 Plants to Feed the Bees
Easily my favorite field guide ever made, this book is a must have. It has a design that invites you to look through the book. It has regional guides, sun and soil requirements, height and an icon key for pollinators as well as basic information for each plant.
Kaufman Field Guide to Insects of North America
Kaufman Field Guides are my go-to choice for identification. The insect guide is a densely packed guide with real size indicators on every page. All of the insects featured are photographs. This guide has larger then average sections on Beetles and Moths.
Kaufman Field Guide to Butterflies of North America
Kaufman Field Guides are my go-to choice for identification. The butterfly guide devotes more time to each species and includes a regional guide for location
National Wildlife Federation's Field Guide to Insects and Spiders of North America
NFW's field guides feature, on average, just three species per page. Some include various life cycles of the species, which is not something many guides do and can be incredibly helpful. All images are photographs and have tips for telling one species apart from another.