Larger grain borer

Definition

A common name for Prostephanus truncatus, a small beetle (family Bostrichidae, order Coleoptera) that is a destructive pest of stored grain, particularly maize and dried cassava. The name distinguishes it from the related lesser grain borer (Rhyzopertha dominica), which is approximately half its size (3 mm versus 6 mm). Native to the Neotropics, it was introduced to West Africa in the early 1970s, reportedly via food aid shipments, and has since become a major post-harvest pest in the region. Under optimal conditions (32°C, 80% relative humidity), it completes its life cycle in about 27 days.

Etymology

English common name coined to contrast with the lesser grain borer, reflecting the relative body size of the two species.

Example

In West African maize stores, the larger grain borer can cause losses exceeding 30% within a few months, with larvae and adults both tunneling extensively through kernels and producing large quantities of frass that further degrades grain quality.

Synonyms

• LGB
• Prostephanus truncatus

Related Terms

• lesser grain borer
• stored-product entomology
• post-harvest pest
• Bostrichidae
• grain storage loss
• Rhyzopertha dominica

Usage Notes

The term is always used in contrast to the lesser grain borer; neither name is used without reference to the other. In scientific literature, the binomial Prostephanus truncatus is preferred. The abbreviation LGB is common in agricultural extension and pest management contexts. Despite the name, the beetle bores into grain rather than merely feeding on the surface.