Thursday, June 14, 2012

Review: Dragonflies and Damselflies of the East

The Peterson Field Guide to Moths of Northeastern North America, released this spring, filled a major field guide gap for people who are interested in learning about insects. Another gap was a comprehensive field guide to odonates in eastern North America. (The insect order Odonata includes both dragonflies and damselflies; it is common to use the generic terms "odonates" or simply "odes" to refer to them as a group.) Dennis Paulson has attempted to address this gap with his new Dragonflies and Damselflies of the East, published by Princeton University Press this winter.

This gap was not quite as critical as the lack of a moth guide since alternatives existed. Dragonflies through Binoculars already covered North America. However, it does not include damselflies, and its small photos make it hard to use. Several excellent guides exist at the state level, such as the Field Guide to Dragonflies and Damselflies of New Jersey. These only cover a handful of states, though they may be useful in adjacent states as well. Dragonflies and Damselflies of the East steps into this gap and fills it well.

The new guide complements Dragonflies and Damselflies of the West by the same author. Together the two volumes cover all 462 damselfly and dragonfly species in the United States and Canada; 336 of those are included in Dragonflies and Damselflies of the East. The eastern guide covers the area east of a line from Ontario to Louisiana. One of the interesting points about odonate distribution is that they are more diverse in the east than in the west, and within the eastern region they may be more diverse in northern states than in southern states. Sussex County, New Jersey, currently has the highest odonate species list of any U.S. county. One reason for this is that odonates are aquatic as larvae, so temperate wet regions (like the northeast) are likely to support more diversity than hot, dry regions (like much of the west).

A lengthy introduction covers the basics of odonate natural history, from their anatomy and life cycle to research and conservation issues. Species accounts follow, starting with damselflies and moving on to dragonflies. Paulson includes some notes on the common characteristics of each family and each genus before describing the species from that group. Species accounts include a basic description, tips for separating the species from similar species, notes on their behavior and life cycle, typical habitat, approximate flight season (which varies regionally), a range map, and one or more photographic illustrations. Usually there are at least two photos, for male and female. I feel some of the photos could stand to be a little larger, but they are adequate for seeing the necessary features. Most of the dragonflies are shown perched, but a few (especially darners) are shown in flight. In addition, there are diagrams showing the reproductive parts for male and female damselflies and dragonflies. This is a critical point since many species can only be identified via examination of their reproductive parts in the hand. The guide is formatted so that descriptive text and photos for each species appear on the same page (or pages); diagrams of reproductive parts are grouped together by genus.

The photos in this guide are printed with their original backgrounds. I have come to prefer the format in which insects are removed from their backgrounds and edited to enhance key features — basically the format pioneered in Kenn Kaufman's field guide series, followed by the Peterson moth guide, and taken in a slightly different direction in The Crossley ID Guide. I think that format is more suitable for seeing important features and comparing similar insects (or birds) without distracting elements like branches or stones. Granted, this may be more difficult to pull off with odonates than lepidopterans because of their intricate wing structure, but it should still be possible. This is one area where I think someone could improve on Paulson's guide, and I would like to see another author give it a try.

In the meantime, Dragonflies and Damselflies of the East is an excellent identification guide and a substantial improvement over existing references. Professional and amateur dragonfly and damselfly observers will want this book.

This review was based on a review copy provided by the publisher.