The pine butterfly, Neophasia menapia (Felder and Felder), infestation on the Nezperce National Forest was aerially surveyed in mid-August 1972. A followup ground evaluation was made in September. Results of the survey show the infestation has increased substantially in intensity and size. The infestation was first reported in 1971 when 4,200 acres of aerially visible defoliation were detected along the south-facing slopes of the Salmon River breaks east of Riggins, Idaho. Approximately 22,000 acres of defoliation were mapped during the 1972 aerial survey. In addition to the infested areas east of Riggins, defoliation exists as far north as Slate Creek and also on the "island" to the south (Fig. 1). Defoliation intensities range from just detectable to complete removal of the foliage. Most of the trees still have their 1972 needles.