General Information

Common name: Sorghum midge
Scientific name: Contarinia sorghicola
Diptera:Cecidomyiidae

Host plants

Sorghum and Johnsongrass

Distribution

Found in areas where Sorghum and Johnsongrass are growing

Damage

The larva feeds on the fluids of a developing seed which results to empty and/or shriveled and discolored seed coats. A damaged sorghum head is pinkish, small, blasted or compressed, wand has undeveloped and/or missing seeds.

Description

The egg is white, 0.3 by 0.6 mm long, cylinder-shaped, and is attached to the spikelet by a tapering stalk. The egg hatches in 2-3 days.

The larva is creamy and changes to a pinkish-orange as it grows. It has rasping mouthparts. A mature larva is flat, 1.5 to 2.0 mm long, spindle-shaped, and tapers to a point at the head. The larva stage requires 9 to 11 days before reaching maturity. It sleeps inside a cocoon that it spun within the spikelets of sorghum.

The pupa is orange at first but changes to near black on all body parts except the orange abdomen. Its body colors are retained when a pupa becomes an adult. A pupa moves to the tip of the glume as emergence nears. A sign of emergence is the whitish-cast skins protruding from the glume tip. The pupal stage requires 2 to 3 days before adults emerge.

The adult is an orange fly or gnat, tiny, and fragile looking. The male lives only for a few hours and measures about 1.3 mm long, while the female is 1.6 mm and lives for only one day. A female lays 30 to 100 eggs, singly, in the glume, within the flowering spikelets, or on the seed husks. About 90% of the eggs are laid during the four days following plant-head emergence. The life cycle of the midge is about 14 to 16 days.