New host plants and other observations are presented for North American weevils (Coleoptera: Curculionidae) with larvae that feed on leaves. Circaea lutetiana L. (Onagraceae) is confirmed as a larval host of Dietzella zimmermanni (Gyllenhal) and the oviposition habits of this species are described for the first time. Lysimachia borealis (Raf.) U.Manns and Anderb. (Primulaceae) is newly reported as a host of Pelenomus sulcicollis (Fåhraeus), and observations of the eggs and larvae are compared with a century-old account of this species. Anaphes Haliday (Mymaridae) was reared from an egg of P. sulcicollis. New distribution records are given for the Parthenocissus Planch. (Vitaceae) leafminer Orchestomerus eisemani Yoshitake and Anderson, and its habits and phenology are discussed, along with an unusual rearing from Vitis aestivalis Michx. Betula alleghaniensis Britton, B. lenta L., B. papyrifera Marshall, Carpinus caroliniana Walter, and Ostrya virginiana (Mill.) K.Koch (Betulaceae) are newly reported as larval hosts for the leafminer Orchestes mixtus Blatchley, and Zagrammosoma interlineatum Girault (Eulophidae) is newly reported as its parasitoid. Amelanchier Medik. spp., Aronia melanocarpa (Michx.) Elliott, Prunus americana Marshall, P. maritima Marshall, P. pensylvanica L.f., P. persica (L.) Batsch, P. serotina Ehrh., and Sorbus americana Marshall (Rosaceae) are new larval hosts for the leafminer O. pallicornis Say, and its parasitoids include Chrysocharis cf. nephereus (Walker) and C. pentheus (Walker) (Eulophidae). Records of other Orchestes spp. on Alnus Mill. are given, including the first rearing of O. testaceus (Müller) from A. serrulata (Aiton) Willd. The leaf mine is described for the first reared specimen of the Salix L. (Salicaceae) leafminer Tachyerges niger Horn.