Wireworms are an increasing threat to the sustainable production of cereal, potato and other crops in Montana since the delisting of lindane, an effective and inexpensive insecticidal seed treatment. With this study, we have initiated long term research to investigate the diversity of wireworm species infesting Montana's cropland. Canister-type bait traps were mailed to collaborating producers who buried them in established cereal fields for 10–14 days, and then returned them to Montana State University where the wireworms were identified to species. A total of 61 cereal fields in 12 counties were surveyed during 2011; 67 fields in 24 counties during 2012; and 66 fields in 16 counties during 2013. Wireworms were caught in 36.8% (46/125) of cereal fields with no prior known history of wireworms, averaging 0.5 larvae per trap. Wireworms were caught in 62.7% (37/59) of fields with a reported history of wireworms, averaging 4.1 larvae per trap. The prairie grain wireworm, Selatosomus aeripennis (Kirby, 1837), was thought to be the most common species in the region. However, Limonius californicus (Mannerheim, 1843), L. infuscatus Motschulsky, 1859, Hypnoidus bicolor (Eschscholtz, 1829) and Aeolus mellillus (Saylor, 1836) were identified as the most common species in this study. Additionally, 2–3 different species often infested the same field.