Flour beetles (Tribolium confusum)


Flour beetles are tiny beetles commonly found as a pest in processed grains. Chances are that you have consumed a few in your food without knowing it! These beetles can be easily reared en mass in a very small container and reared on processed grain products.

Availability: These need to be ordered and will be available after spring break. Contact Liz (eegraham@life.uiuc.edu) to schedule a pickup time (right after class is convenient). We will provide you with several flour beetles. They will come in a small plastic container with just enough flour to get them home, so make sure your container is set up and ready to go BEFORE you pick them up.

Housing and food: Keep beetles in a glass jar filled about one-fourth to one-third full of feeding medium (recipe follows). Be sure to have a sturdy lid, since flour beetles can easily escape through cracks or chew through cardboard and soft plastic. The beetles live IN the medium. Add more medium as needed. Beetles do not need a source of water.  Humidity should be maintained at 70% though, this can be done by adding a small slice of potato or lettuce to your jar.   Change the slice when it becomes dry or moldy. 

Feeding medium: Mix 4 parts white flour, 4 parts whole wheat flour, and 1 part brewer's yeast. (You will probably have reasonably good success using just whole wheat flour, but why take chances?)

Cover the top of the jar with cloth (NOT a screw top as you want air to enter the jar).

Notes: Flour beetles are cannibalistic when they are overcrowded. Adults will eat eggs and larvae will eat everything. They reproduce very quickly (females can live for a year or more and lay 400 to 500 eggs), so check your colony frequently for overcrowding.  A good way to do this is sift through the feeding medium with a wire strainer - the kind you keep in your kitchen. Keep in mind that these beetles can escape INTO your kitchen! Overcrowding also increases the chances for transmission of a protozoan parasite, Adelina tribolii, which can kill all of your flour beetles.  Beetles under stress (overcrowded, too hot, not enough food) often produce a gas containing certain quinones which can cause the appearance of aberrant forms of Tribolium and can even kill the beetle colony.