Sorghum Shootfly

Pests of Field Crops in Southern Africa

SORGHUM SHOOTFLY

(Diptera: Muscidae)

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Text Box: The sorghum shootfly, Atherigona soccata, is a small fly, not unlike a small housefly in appearance, which in some years infests late-planted sorghum. The flies have pale grey head and thorax and yellowish abdomen with paired brown spots. The larvae are legless, white maggots which reach a length of about 10 mm. TOP

Text Box: Besides sorghum, this pest may attack maize, millets, wheat and some common grasses. TOP

Text Box: The larval stages enter the plant through the whorl and kill the growing shoot, giving rise to the “dead heart” symptom. Examination of affected plants indicates a rotten area at the base in which the maggot or pupa may be found. This usually results in tillering by the plant. Extensive damage is not common, but portions of a land may be affected, particularly in late-planted crops. TOP

Text Box: Whitish, cylindrical eggs are laid on the underside of leaves 10 to 25 days after emergence. Hatching takes place in 2 to 3 days, and the tiny maggots bore through the whorl. In one to two weeks the larval development has passed through three stages and pupation takes place in the damaged area, or very occasionally in the soil. After about a week, the adults emerge to reinfest late-developing shoots. TOP

Text Box: Control of this pest is not usually necessary. It can be largely avoided through early planting, since the flies will only infest young seedlings up to about 25 days old. Sorghum plants do compensate by developing tillers, which may mature not much later than the main shoot, unless the infestation is very heavy. Chemical control in late-planting situations, although very costly, may be achieved through the use of systemic granules applied at planting, in the same way as is done for stem borers. TOP

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