STEM BORERS OF CEREAL:
Economic importance: the larvae bore into the stems and destroy the tissues.
Control measures: (i) spray with appropriate insecticide eg. Veto X 85 (ii) practice  (iii) badly affected plants should be destroyed. Grain weevils of stored produce:

GRAIN WEEVILS OF STORED PRODUCE:
Economic importance: larvae bore into, pupate in, and feed on seed causing reduction of grain   to powder.
Control measures: (i) treat sack with lindane dust during storage at 0.5% (ii) fumigate with BHC powder
COTTON STAINER:
Economic importance: it causes leaf distortion and transmission of virus disease. It also feeds on the content of the boil.
control measure: hand picking of insects.
CASSAVA MEALY BUG:
Economic importance: strong growth disturbance of the terminal shoot. Which become  stunted and deformed, Internode length is reduced causing twisted stems
control measure: (i) early rainy season is recommended (ii) treat cuttings with hot water (250C for ten minutes) or dip into a o.1% lime throated solution to kill insects before planting