Recent advances in the arts make it possible to illustrate books at much less cost than formerly. An important invention is the process of printing in three colors from half-tone plates. The author of this manual was one of the first to use this process in illustrating a work upon the lepidoptera. When The Butterﬂy Book appeared he received letters from many scientific friends expressing their wonder. Among those who wrote to him was Dr. Samuel Hubbard Scudder, the Nestor among American lepidopterists, who has since passed away. He said: I am simply astonished at the fidelity to nature displayed by the plates in your book, and at the low price at which the new process permits it to be sold. That The Butterﬂy Book met a real need is shown by the fact that more than thirty thousand copies have already found purchasers. It is, however, a biggish book. The publishers, Messrs. Doubleday, Page Co., have asked me to get up a little pocket manual of the butterﬂies, similar in form to the Flower Guide, which has been most cordially received by the public. I have therefore prepared the following pages, to which in the gracious phrase of our forefathers I now invite the attention of the gentle reader.