Harris drew and engraved his own illustrations. The second edition (1778) was considerably expanded, and with four more plates than the first, for a total of 45. Some of the hand-colored copies were hand-colored by the author. "Harris began to take an active interest in entomology about the age of twelve and ... was an accurate and original observer. He was, it is believed, the first to draw attention to the importance of wing neuration [the arrangement or distribution of nerves] in the classification of lepidoptera and upon this principle he arranged the species in his published works, illustrating them in colour with a high degree of accuracy. Harris certainly contributed much to the knowledge of the science and was one of the leading entomologists of his century. He was also a miniature painter of no mean accomplishment" (Lisney p.156). Lisney identifies different states of plates in the first edition, and different issues of the second edition.