**Sorghum Midge** (*Stenodiplosis sorghicola*) is a highly destructive, specialized gall midge (a type of fly) and is the most important insect pest of **grain sorghum** and other related wild grasses globally. The conflict is total yield loss: the minute fly lays its eggs inside the open flowers (glumes) of the sorghum head. The larvae (maggots) then feed on the developing ovary, preventing the formation of a kernel, which results in a **”blasted” head** that contains no grain, leading to massive economic loss.
Taxonomy and Classification
Sorghum Midge belongs to the order Diptera (Flies). They undergo complete metamorphosis. The entire life cycle, from egg to adult, takes only 14-16 days, allowing for 9-12 generations in one season, which results in explosive population growth and continuous pressure during the vulnerable flowering period.
Physical Description
Adult Midge is minute, 1.5-2 mm long.
- **Adult Fly (Key ID):** Tiny, delicate, orange-red fly with translucent wings and long antennae. They are rarely noticed in the field.
- **Larva (Maggot – Key ID):** Tiny, orange-red maggot found hidden inside the unfertilized sorghum flower.
- **Damage Sign (Key ID):**
- **Empty Heads:** Sorghum heads appear normal in size but contain few or no developed kernels, often with the glumes closed and empty.
- **Flower Loss:** The flower structures appear “blasted” or white/shriveled after the maggot has fed.
- **Silk Strands:** Fine, white silk-like strands may be visible on the flower/seed head (where the maggot pupates).
- **Conflict:** Severe crop failure (no grain set).
Distribution and Habitat
Sorghum Midge is found worldwide in all major sorghum-growing regions. Their habitat is the flowering head of the sorghum plant, where the female only lays eggs when the flower is actively blooming (anthesis).
Behavior and Conflict
The conflict is defined by its rapid, hidden, and synchronized attack.
- **Vulnerability Window:** The plant is vulnerable for only a few hours while the flowers are open, but the midge is able to precisely target this window.
- **Field Variation:** The sequential blooming of different sorghum fields in a region ensures a continuous food source for the midge population throughout the growing season.
- **Mothballing:** The larvae can enter diapause (dormancy) within the silk strands of the head or ground litter, surviving harsh conditions and emerging the following season.
Management and Prevention
Control is integrated pest management (IPM), with a heavy focus on genetic and timing control.
- Planting commercially available **midge-resistant sorghum hybrids** is the most effective long-term solution.
- **Uniform Planting:** Plant large fields uniformly to ensure all plants flower simultaneously, reducing the vulnerable window for the midge.
- **Stubble Management:** Plow under or destroy crop residue after harvest to reduce overwintering midge populations.
- Apply a registered insecticide only when adults are seen (monitoring is crucial) and the crop is in the susceptible flowering stage. Timing is critical, usually at 50-75\% bloom.
Conservation and Research
Sorghum Midge is managed as a severe, high-priority agricultural pest. Research focuses on identifying new genes for midge resistance in sorghum, improving monitoring traps, and exploring the use of parasitic wasps for biological control.