Pictorial Key for Identification of Immature Stages of Common Ixodid Ticks Found in Pastures in Oklahoma

Abstract. Many species of ixodid ticks in the United States are parasitic on cattle and pose a threat to veterinary and public health for those engaged in occupations in pasturelands. While encountered often, nymphs and larvae of the most common tick species can be difficult to identify, yet research associated with tick ecology and epidemiology of tick-borne infection requires proper identification. High-quality images were prepared of the larval and nymphal stages of the most common species of ticks in Oklahoma pastures: larvae of the lone star tick, Amblyomma americanum (Linnaeus), Gulf coast tick, Amblyomma maculatum Koch, winter tick, Dermacentor albipictus (Packard), American dog tick, Dermacentor variabilis (Say), blacklegged tick, Ixodes scapularis Say, and brown dog tick, Rhipicephalus sanguineus (Latrielle); and nymphs of A. americanum, A. maculatum, D. variabilis, I. scapularis, and R. sanguineus. A dichotomous key and pictorial guide for each life stage were prepared.