Scientific name: Rhyzopertha Dominica
2.3-3mm in length, the Lesser Grain Borer has a long, cylindrical body that is a dark red-brown/black colour. The head and abdomen feature rows of tiny indentations and the antennae finish with 3 larger segments that form a club.
The Lesser Grain Borer originated in South America but is now a cosmopolitan pest especially in warmer countries.
It is not cold hardy pest and development is limited at temperatures less than 23°C. Infestations are typically in grain stores including ships holds, flour mills and animal feed mills. They have also been recorded in woods and books.
In Australia and India, it is a serious pest of grains. Grain borers are associated with a wide variety of vegetable materials including wheat, barley, maize, rice, millet, sorghum, dried potatoes, dried herbs and biscuits.
The female lays single or multiple eggs on the outside of the grain but the egg goes through its developmental phases in the hollowed core of the grain.
An infestation is characterised by a sweet yet unpleasant, musty smell from excretions and shed skin.
Lesser grain borers are primary pests of grain and can attack undamaged grain, rendering it susceptible to attack by secondary pests.
Both the adults and larvae feed on the grain creating a floury dust and potentially, leaving little behind except for the empty husks.
The adults are active and may infest a large number of kernels whilst the larvae penetrate kernels and develop within the grain.
They significantly reduce the market value of stored grain.