This study was undertaken to evaluate and determine morphological characteristics which might prove valuable in the identification of the larvae of the following species of ticks of the genus Dermacentor Koch: D. albipictus Packard, D. andersoni Stiles, D. hunteri Bishop, D. parumapertus Neuman, and D. variabilis Say. A taxonomic key for the identification of all of the Canadian and United States species of the larvae of the genus Dermacentor Koch cannot be constructed until specimens of D. halli and D. occidentalis have been examined. However, the followng conclusions were reached regarding the species studied: 1. Position of setae is of no value in differentiation between the species studied. 2. The length of the scutal, sternal, premarginal, preanal, and coxal seta- are of value in the separation of the species studied. 3. The dermal sensilla was the only sensilla found to have any taxonomic value in the identification of species. 4. The determination of the degree of taxonomic significance of the leg sensillae awaits improved techniques in spreading, mounting and clearing specimens. 5. The size of the hypostome, palps, and tectum is taxonomically important in identification of species. 6. The presence or absence of coxal spurs was shown to be of questionable taxonomic significance. 7. The presence or absence of cornua is important in distinguishing between the species studied.