The systematics of this group of insects is reviewed in its entirety. Keys to related genera and to the North American and world species are given, together with illustrations. Where necessary, all species are redescribed and three new members from California are added to bring the total number in the genus Scirtothrips to 35. The distribution and host plants are given for each; three species are of economic importance, particularly those attacking citrus in South Africa and southwestern United States. Species formerly included in the group are listed, and five additional species are removed. A complete bibliography is appended.
