This seminal work on syrphid flies, also known as hoverflies, is a must-read for anyone interested in entomology. Williston's careful observations of these fascinating creatures, as well as his classification system, have had a lasting impact on the field of biology. Whether you are an experienced scientist or simply an amateur naturalist, this book is a treasure trove of information on one of the most diverse and important groups of flies.This work has been selected by scholars as being culturally important, and is part of the knowledge base of civilization as we know it.This work is in the "public domain in the United States of America, and possibly other nations. Within the United States, you may freely copy and distribute this work, as no entity (individual or corporate) has a copyright on the body of the work.Scholars believe, and we concur, that this work is important enough to be preserved, reproduced, and made generally available to the public. We appreciate your support of the preservation process, and thank you for being an important part of keeping this knowledge alive and relevant.