Paraclemensia acerifoliella (Fitch) caused serious damage to the foliage of sugar maple (Acer saccharum) in northern New York in 1958 and 1959. This Incurvariid is reported from a work already noticed [R.A.E., A 38 444] to have one generation a year; the adults emerge in May and deposit eggs in the leaf tissues, and the larvae mine the leaves for 10-14 days and then live as case-bearers until late August or September, when they fall to the ground and pupate in their cases. In a test in 1959, spraying with 2 U.S. gal. 9 per cent. DDT in fuel oil per acre from an aeroplane on 22nd-23rd July, when the larvae had ceased mining and before foliage damage was severe, gave good control. Examination on 15th August showed that leaf-cutting activity had not progressed since the treatment in sprayed stands, in which the foliage remained green, but had continued in unsprayed stands, in which the foliage was badly damaged and turning brown.