The first and third larval stages of Nearctic Anisotoma blanchardi (Horn, 1880) are described in detail and figured for the first time; measurements and chaetotaxy of head, mouthparts, thorax, abdomen, leg and urogomphi are given. Larval morphology of the blanchardi group is discussed. The blanchardi species group, proposed after a study of adult characters, is very important phylogenetically because it is a basal group in the genus and sister group to all the remaining groups. Larval characters confirm the monophyly of the group. The common larval characters of the blanchardi species group are: (i) presence of primary setae below the posterior row of terga, (ii) secondary microsculpture on the head, dense, present from the base of the head to the anterolateral arms of the epicranial suture and fronto-clypeal furrow, (iii) sclerotization around sockets of primary posterior setae of thorax of instar III, (iv) presence of clypeal furrow in the third stage, (v) presence of setae Dc1, Dd1, Dc2, Dd2a on head in instar III, (vi) urogomphomere 1 and 2 similar in length and proportion.