Note: The larger grain borer originates from the Americas but has spread to Africa and is now spreading fast to all African countries which grow maize and cassava. Our neighbouring countries were invaded by larger grain borer several years ago, but it was recorded for the first time in Namibia during 1998. COMMON NAMESLarger grain borer; greater grain borer (English)PEST STATUSThe larger grain borer was only found recently in Namibia and the pest status and distribution is unknown at present. Larger grain borer only attacks stored maize and dried cassava.DESCRIPTIONThe larva is white and has parallel sides i.e. it is not tapering like many other larvae. The adult beetle is black and 3-4 mm long. The body is cylindrical and short. The shape of the tail end is unusual, it is not rounded like other beetles but more resembles a slanted cut.Larger grain borer behaves like a typical primary storage pest, in that it attacks whole cobs and kernels. The adult beetles attack maize in the fields just before harvest and is carried into stores in the cobs. The adult beetle bore into the hard maize cobs and can penetrate wood. During tunnelling beetles produce a lot of maize dust. Eggs are laid in the tunnels and the larvae thrive on the dust produced. The larger grain borer can operate at very low moisture levels, at which other storage pests cannot survive. CONTROLTry to avoid using chemicals in stored food. If chemical control is still considered necessary, please contact the FSRE pest officers for precise advice on chemical control. The contact numbers and addresses are listed on the cover.OTHER NOTESPheromone traps were distributed to agricultural extension staff in 1997 by the Ministry of Agriculture, Water and Rural Development (Phytosanitary Unit). The aim was to monitor the potential presence of larger grain borer in Namibia. One of these traps caught the first specimens of the pest in Namibia.
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