In the United States, it occurs from Virginia to Florida and as far west as Texas. Areas where sorghum has been grown for several years and where Johnson grass is prevalent are typically infested. Host Plants - Johnson grass and grain sorghum are the primary host plants of the sorghum midge. Although the midge has been reported on and reared from 14 other grasses, these hosts generally are not considered suitable for normal midge development. Damage - Larvae of the sorghum midge feed on the ovary thereby preventing normal seed development.
Infested heads appear blighted or blasted and produce small, malformed grain.
Life History - Sorghum midges overwinter as larvae in aborted sorghum spikelets. They spin cocoons inside the spikelets where they may remain in a resting stage, resistant to cold and desiccation for as long as 2 or 3 years. Under favorable conditions, however, pupation and emergence take place the following spring at about the time Johnson grass begins to bloom. After mating, each female then deposits 30 to 120 eggs, singly, in the flowering spikelets of this grass. The eggs hatch 42 to 60 hours later, depending upon the temperature.