Populations of the sorghum midge, Contarinia sorghicola (Coquillett), are maintained at low levels in johnsongrass, Sorghum halepense (L.) Pers., from late spring to mid-summer. A slow buildup occurs on grain sorghum, S. bicolor (L.) Moench, during early August, and numbers capable of causing severe yield reductions are reached after ca. 20 August. Fields planted prior to 15 June will likely escape midge damage. Those planted between 15 and 22 June may or may not escape damage, depending on the season. Virtually all plantings made after 22 June risk severe midge infestations and yield reductions.
