Newswise — Fruit flies are no griffons, but they are more beautiful and varied than one might think. Thomas Werner and John Jaenike detail them in a field guide for the Midwest and Northeast.

Werner, an assistant professor of biology at Michigan Technological University, has been collaborating on the project for nearly five years with Jaenike, a professor of biology at the University of Rochester.

"Many people think the only fruit fly species that exists comes in with the bananas," Werner says. That would be the famous Drosophila melanogaster, the long-toiling workhorse of genetics. But there is actually a great diversity of species closely related to “the fly,” and they vary greatly in appearance, ecology and behavior.

A lifelong butterfly collector, Werner began studying fruit fly genetics in graduate school. Until he met Jaenike, he says he only saw fruit flies for the research value. But then during a work trip connected to a mentorship program, Jaenike showed Werner how to catch and identify fruit flies out in the woods; Jaenike could identify the tiny creatures just by sight—no magnification—and Werner says he was instantly hooked. He went back to his hotel room that evening to make a rough draft of the first regional fruit fly field guide produced in 96 years.

Their completed book Drosophilids of the Midwest and Northeast is available online and covers 55 species of fruit flies (technically, species of the family Drosophilidae), with detailed images and descriptions. Although the subject is small to behold, the book reads more like a birding guide and opens up a whole new world people might ignore on walks through the woods.

Each image in one of Werner's close-ups is the compilation of 50 to 80 photos taken under a microscope. They take two hours to complete on average.

Werner jokes that the fine-tuned work is for the dark days of winter. For years, he has stayed late after work in the snowy months to carefully clean, refocus and enhance the fruit fly images in order to bring out features like key wing spots, body color patterns and size differences between males and females.

The key is that by using fresh fruit flies, the images are more like what collectors would see in the wild or under the microscope when they bring the flies back to the lab. Jaenike and Werner made a point of showing the typical range of phenotypic variation as well, not simply a single "type" specimen. The detail and crispness make the field guide as unique as the fruit flies throughout its pages.