If you want to have a field guide built for a certain location, choose field guides that only focus on specific areas, states or regions. There are lots of field guides for insects that have that offer these specifics.
Choose a field guide solely based on the experience level of the user. The book, "The Insect Book: A Guide to the Collection and Care of Common Insects" will very suitable to beginners. The said book is also intended for children ages 8 and up.
On the other hand, the "A Unique Guide to Insects in North America" is a useful reference to those who love to adventure outdoors. It tackles about common insects that you can find in urban areas and gives you on a step-by-step basis on how to properly identify different species around you.
Insects are the most dominant and numerous form of life on the planet. Everyday, we encounter them be it in rural or urban communities. The need to identify them properly stems from the fact that we want to know how these creatures around us could affect our lives and our loved ones.