Leptocorisa acuta, Rice earhead bug, Paddy stink bug

(Hemiptera: Coreidae)

Host:This pest feeds on a variety of graminaceous plants, e.g. rice, wheat, sugarcane, maize, millets, bajra etc. Flowering rice is the preferred host.

Damage: The pest immigrates in the crop in the flowering stage and feeds on the milky grains and on the sap of the peduncle and leaves. Yellow spots appear on the leaves due to excessive sucking. The empty grains turn whitish and show a puncture mark. The characteristic damage is called chaffy grains. Infestation is severe in irrigated and heavy rainfall areas.

Life cycle: Adult are very active bugs, about 15 mm long, having narrow and long body and greenish-brown to yellowish-brown colour. Antennae and legs are also narrow and long. They are diurnal but most active during morning and evening when they look for the flowering crops. Their presence can be easily detected by the characteristic foul odour that they emit.

Female can lay 200-300 eggs in its lifetime. Eggs are laid in batches of 20-30 in 2-3 rows along the midrib on the upper surface of the leaf blade. Nymphs are greenish, slender and similar to the adults in appearance and sucking habit. There are 5 nymphal instars and total nymphal period is 25-30 days. Nymphs being wingless must stay on the crop till they become adults and grow wings. The bug can complete 4-5 generations in a single season.

Distribution: The species occurs throughout Asia up to New Guinea and northern Australia.

Control: Collection and destruction of the bugs by netting or in light traps can be done in smaller areas. Removal of grasses and other weeds from bunds and surrounding areas reduces population. Dusting of the crop with 5% BHC, Malathion or aldrin @ 15 kg per hectare effectively controls the pest. Application of granules of carbofuran or diazinon has also been found effective.