Lepidopteran leaf mine from the early eocene wind river formation of northwestern wyoming.

A lepidopteran mine, probably of Phyllocnistis, on a leaflet impression of Cedrela (Meliaceae) discovered in late early Eocene strata near Dubois, Wyoming, is the earliest record of leaf mining and of the Phyllocnistidae. Considerable prior evolution of the mining habit, antiquity of the Cedrela-Phyllocnistis relationship, and subtropical climatic conditions are indicated.