Insects: Their Natural History and Diversity. Stephan A.
Marshall. 718 pp. Firefly Books, 2006. $95.
Like most people who work with insects, I cut my teeth identifying
insects on what are called "dichotomous keys"—a
series of bifurcating questions about a specimen that must be
answered to ascertain the insect's family. I grew to love this
system of identification in a masochistic sort of way, and I
discouraged my students from "picture-booking" insects
because I wanted them to learn the critical characteristics of each
family. Along the way I filled students' heads with charming trivia
about the spurious vein of syrphid flies, the foot-shaped anal loop
of libellulid dragonflies and the split mesopleuron (a region of the
thorax) of pompilid wasps. I never wondered much about alternative
methods because this was how I had been taught. Yet whenever a
student asked me how I knew that the moth at the blacklight trap was
a tiger moth, I stumbled with a Gestalt definition of the taxon. I
certainly didn't examine the wing veins of the living specimen.
Last year I heard a lecture by Bruce Kirchoff, a biologist at the
University of North Carolina in Greensboro, about a Gestalt method
of recognizing taxa. What he described fit rather well with the way
I identify insect families in the field. In a nutshell, the Gestalt
method suggests that the way we learn taxa is that, rather than
focusing on critical characteristics, we use a type of holistic
processing that allows us to recognize and categorize groups based
on a constellation of characteristics and how they relate to one
another. Often this processing goes on without much thought. We just
"know" when we are looking at, say, a pentatomid bug, but
we are not quite sure why.
This is the background with which I approached Stephen A. Marshall's
book Insects: Their Natural History and Diversity. This
guide to the identification and natural history of the insects of
eastern North America contains incredibly detailed and beautiful
photographs of representatives of the most common insect families.
The preface outlines the way the book is meant to be used: You are
first instructed to go to a set of pictorial flowcharts in the back
of the text. These are dichotomous keys, to be sure, but they are in
a refreshing new color-coded format with figures scattered
generously across the page—right where you need them. No more
"if yes go to couplet 48 on page 337" or "see figure
14G." Once you have an informed guess at the order and family,
you are directed to a family section with detailed photographs,
which richly depict the diversity of representatives of each family.
This is where Gestalt learning takes over. The family theme is
immediately obvious, and the illustrations show its many variations.
There is also a useful text description of each family, packed with
the group's natural history. I cannot wait to try this text in my
insect-biology class. Will my students learn their insect families
as well as their predecessors did? I think they will, and I expect
they will find the process much more enjoyable.
That all said, I do have a few problems with the book. I wish it
contained more morphology, physiology, behavior and ecology at the
beginning so that I could use it as the sole text for an
introductory course in entomology. For years students of insect
biology have been forced to purchase two texts each semester, and
that requirement seems unlikely to change. Also, I think the author
should consider separating the flowchart keys into a slim volume
that a student could carry in the field, leaving the rest of the
massive 7-lb. tome back in the lab to use as a reference.
Overall, though, this is an outstanding contribution to entomology.
It will play an important role in the training of insect lovers for
the foreseeable future.