Stored Grain Insects



Broadhorned flour beetle

Gnatocerus cornutus



Adult broadhorned flour beetle (Gnatocerus cornutus)
Courtesy of Degesch Inc.

The adult broadhorned flour beetle (Gnatocerus cornutus) is about 3.5 - 4.5 mm long and red-brown in colour.The feature which easily distinguishes it from other flour beetles is a pair of broad, stout horns on the mandibles of the male. The eyes are crescent shaped and the adults have been known to fly. The larvae are pale red-yellow and grow up to a length of 9 - 10 mm. They are mobile and not concealed.


Developmental stages
Courtesy of Degesch Inc.

Life cycle
The female broadhorned flour beetle will lay up to 400 eggs during a five-month egg-laying period. If conditions are optimum (24 - 30 ?C and 66 - 92% r.h.) the life cycle can be completed in approximately 60 days. The egg incubation period lasts 7 days and the larvae develop in approximately 40 days. There are seven larval instars and pupation lasts for 10 days.

Damage caused by broadhorned flour beetle
Courtesy of Degesch Inc.

The broadhorned flour beetle feeds mainly on grain products and is frequently found infesting flour and feed mills. The larvae have also been found feeding on flour, corn meal, beans, dog biscuits, corn, pancake flour, yeast cakes, bran, farina and sugar cane.

Broadhorned flour beetle
Courtesy of CSIRO Division of Entomology