The genus Ostrinia is revised and the species limits, phylogeny, host relationships, geographical distribution, and the economic implications of species limitation are briefly discussed. Twenty species and 24 additional subspecies are recognized, of which 5 species and 19 additional subspecies are described as new. One new name is proposed for a homonym and a number of changes of synonymy and status are made.

Electrophoretic analyses of the (Z) and (E) pheromone-attracted males of Ostrinia nubilalis (Hübner), the European corn borer, in an area of coexistence indicate that these strains are not freely interbreeding. Although the populations are morphologically indistinguishable, studies of allozyme, pheromone, and hybridization suggest that the (Z) and (E) entities are genetically differentiated, perhaps to the status of semi- or sibling species.

Seven species groups of Dioryctria are defined on a combination of external and genital characters. Three American species, Dioryctria rossi Munroe, D. auranticella (Grote) and D. disclusa Heinrich, are referred to the auranticella group. Four Asiatic species are also referred to this group. These are D. okui Mutuura, D. castanea Bradley, D. pryeri Ragonot (= Salebria laruata Heinrich), and D. yiai n. sp. All the species feed on conifers. All except D. okui feed on pine, either cones or shoots, or both; D. okui eats the foliage of spruce.

Dioryctria tumicolella, from pine blister rust, Peridermium spp., swellings on Pinus ponderosa Lawson and Son in British Columbia, Washington, Montana, and Colorado; D. contortella, from Peridermium swellings on P. contorta Douglas in British Columbia, Alberta, and Washington; D. monticolella, from trunks of P. monticola Douglas in British Columbia; and D. banksiella, from trunks of P. banksiana Lambert in Alberta, Northwest Territories and eastward, are described as new species and distinguished from the western D. cambiicola (Dyar) and the eastern D. zimmermani (Grote).

Dioryctria resinosella, a species feeding on red pine cones or shoots, is described as new and recorded from Maine, southern Ontario, Wisconsin, and Minnesota. The new species is distinguished from D. zimmermani (Grote) and D. banksiella Mutuura & Munroe by the differences in wing markings, genitalia characters, and ecological aspects.