Moth-lovers in Great Britain or western North America have some excellent choices for identification guides, such as Moths of Western North America by Jerry Powell. In the eastern U.S., the options are not as good. The most comprehensive option is Charles Covell's Moths of Eastern North America, a long out-of-print guide in the Peterson family, available only as a pricey reprint or hard-to-find used book. This means that the best easily-available resources for identifying eastern moths are the photos at BugGuide and the Moth Photographers Group. These websites have excellent resources, but as both are volunteer efforts, many species (including difficult ones) lack identification notes or even range descriptions.
Most species included in the guide are given a full page account. These show large photos of the adult and the caterpillar. In some cases, the facing page shows one or more similar species with similar life histories for easy comparison. (This is the case for American Idia; the facing page shows Glossy Black Idia, Common Idia, Dark-banded Owlet, Variable Zanclognatha, and Dark-spotted Palthis and is the only place where those species are illustrated in the guide.) A typical species account includes identification instructions for both adults and caterpillars, a range description, and the number of generations per year. Most also include a section called "Nature Notes," or brief remarks on aspects of a moth's life history that do not fit into the other categories. A calendar bar under the photo of the adult shows what time of year each species is active. The introduction includes diagrams of the adult and caterpillar with their body parts labeled; these are a useful reference for interpreting the identification notes.
Despite its lack of comprehensiveness, this guide offers some useful features. I find that it is useful for browsing subfamily and genus groups, even if I cannot find the exact moth species I am looking for. Beyond that, it contains useful information about life histories and anatomical features that may make difficult moths easier to identify. Even though the guide is limited to the north woods region, moth-lovers throughout the northeastern United States can use this guide until more comprehensive guides become available. The guide would be even more useful if it included an identification key similar to those found in the Peterson Guides to Insects or Beetles.
The good news is that some better guides should become available in the very near future. A new guide to the moths of northeastern North America is in the works for the Peterson series. In addition, Sogaard mentions in his introduction that he is working on a new guide called Living Moths & Caterpillars: A Guide to Eastern North America. This means that within a year or two, eastern moth-lovers could have two up-to-date field guides. I would not expect moths like the Olethreutine moth pictured below to become any easier to identify, but at least we will have better resources for doing so. Moths & Caterpillars of the North Woods is a good start in that direction.