Flour Beetle


Actual Size: 3–4 mm

Characteristics: Reddish-brown in color with small, flattened bodies.


  • Do not harm humans or cause structural damage.
  • Feed on grain dust, flour, and milled cereal.
  • Their tiny size allows them to hide in the tiniest of cracks.

Flour Beetle Overview

A number of beetles belonging to the family Tenebrionidae infest flour and related grain-based products and are known as flour beetles. Of these species, the confused flour beetle and the red flour beetle are the most economically important.

Flour Beetle Identification

Adults are small, flattened, reddish-brown beetles about 3/16th of an inch in length. The key identifying characteristic is seen in the antennae of the two beetles. The antenna of the red flour beetle ends abruptly in a three-segmented club, whereas the antenna of the confused flour beetle gradually enlarges into a club consisting of four segments.

The eyes of the red and confused flour beetles wrap around the sides of the head from top to bottom. On the underside of the head, the eyes of the confused beetle are widely spaced from each other, whereas the eyes of the red flour beetle converge more closely. Red flour beetles can fly, especially before a storm, but the confused flour beetle does not fly.

Flour Beetle Threats

Flour beetles will not bite or sting humans, do not cause structural damage and researchers believe that they do not spread disease. They are omnivorous and are extremely important pests of flour, being the most commonly encountered pests in flour mills. They feed on grain dust and milled cereals but are unable to attack sound and undamaged grain.

When the beetles are present in great numbers, they may cause the flour to turn grayish and to mold quickly. Additionally, they impart a disagreeable taste and odor to the flour from a secretion of their scent glands. They infest cereal products and pet foods and are commonly seen in grocery stores and food warehouses. These beetles are then carried into homes in infested cereals, flour, and dried pet foods and from there infest other foods in cupboards and pantries. Being active, they quickly run to cover when disturbed and due to their small size, can invade many types of packaging.

Flour Beetle Extermination & Control

The following prevention tips can help to reduce problems with flour beetles and prevent a flour beetle infestation:

  • Keep a clean kitchen and pantry. Flour beetles can survive on even the smallest bits of grain, so cleaning is a crucial part of controlling these pests.
  • Place infested material into a freezer for four or five days. Beetles cannot survive freezing temperatures.
  • Clean cupboard and pantry shelves regularly, as this will help remove small particles of food that red flour beetles need to survive.

If you have tried all the above measures and still experience flour beetle issues, it is best to consult a licensed pest control operator for interior pesticide treatments.