The life history of the beet leafhopper, Neoaliturus (Circulifer) tenellus (Baker) (Hemiptera: Cicadellidae), was studied on weed hosts in southern New Mexico from January 2008 through December 2009. Weekly counts of leafhopper adults, nymphs, and eggs were taken from London rocket, Sisymbrium irio L., and kochia, Bassia scoparia (L.) A. J. Scott, at two field sites, and the relationship between leafhopper and phenology of the host plant was documented. The presence and abundance of the eggs, nymphs, and adults during the year suggest this species is univoltine in agricultural regions of southern New Mexico, with some evidence of a second generation. Changes in the timing of kochia emergence and the beet leafhopper flights were noted in 2016–2017 and again 2020–2023. Previous studies on voltinism are reviewed for this species, and the implications for management of the beet leafhopper are discussed.