Flour Beetles: A Profile of a Truly Pesky Pest

Posted by Mark A. Puglisi, ACE on Wed, May 17, 2017 @ 12:25 PM

Four beetles may not be as common in homes as termites or cockroaches, but they can surely be an annoyance -- especially if you are a prolific baker or own an in-home baking business. Both these beetles and their larvae can invade not only flour, but also other grain products, rendering your ingredients contaminated and unusable. Read on to learn more about these truly pesky pests and how to keep them out of your pantry.

What Are Flour Beetles?

There are several species of flour beetles, but the two most common are Triboleum confusum and Triboleum casteneum. These are commonly known, respectively, as the confused flour beetle and the red flour beetle. 

Confused flour beetles are black in color. They have six distinct legs and elongated bodies, and they measure between 3 and 6 mm in length. Red flour beetles have a more reddish color, are similar in size, and are able to fly short distances. (Confused flour beetles cannot fly.)

Because the beetles are so small, it can be difficult to tell which type you are dealing with. However, in most situation, it does not really matter whether you have an infestation of red flour beetles or confused flour beetles as the two can be eradicated and managed with the same methods.

What Problems Do Flour Beetles Cause?

Flour beetles are a huge nuisance in grain cellars and warehouses. The adult females lay their eggs in the flour, and about a week later, these eggs hatch into larvae. The larvae look like thick-bodied worms and are yellow in color. They feed on the flour, slowly increasing in size before eventually maturing into adults. 

It's not as common to find flour beetles in households as it is in large warehouses and grain mills, but they are certainly a pest to be aware of if you store and use flour in your home. They will ruin a batch of flour, making it completely unusable, and then hide out in your home ready to contaminate any new flour or grain products you buy.

Once you have flour beetles in your home, you need to take measures to eradicate them. Otherwise they'll just keep destroying batch after batch of flour. It's important to note that, while flour beetles are disgusting, they are not poisonous, do not bite, and do not release any toxic compounds into the flour.

What Are The Signs of a Flour Beetle Infestation?

If you have flour beetles in your home, you may spot the beetles themselves in, on, or around your flour storage containers. You may also see them in and around other grain products like oatmeal and cereal. Though the adults cannot feed on large pieces of grain, they are attracted to the dust and finely milled particles in these grain products.

You may also notice larvae in the flour or grain product. The larvae may appear like small grains of rice, but upon closer inspection, you may notice their segmented bodies and tiny legs. Flour and grain products infested with flour beetles and their larvae eventually begin to smell rancid and unappealing.

What Should You Do If You Think You Have Flour Beetles?

If you catch the infestation early, you may be able to eradicate the beetles with some good sanitation practices.

Start by discarding all of your flour and other grain products -- even bins and bags that do not appear to be infested. (They may be lightly infested with larvae or have eggs laid in them that have not hatched yet.) Dispose of them outside of the home so the insects cannot crawl back out of the trash can.

Next, thoroughly wash and sanitize all containers that were used to hold grain products. Vacuum out all cupboards and shelves where the flour was stored, and then wipe them down with soapy water. Wait a week or two before re-purchasing flour and other grain products. This way, adult beetles may die of starvation before you provide them with a potential new food source.

When you re-introduce flour and grain products to your home, be sure to store them in tightly sealed containers. Do not store your flour or other grain products in the original boxes or bags; flour beetles can chew right through these. Also, take steps to keep your storage area dry, as moisture may attract the bugs. Wipe up any spills immediately, and consider installing a dehumidifier if your pantry or storage area is humid.

If you have ongoing problems with flour beetles, your best bet is to call a pest control company like Greenleaf Organic Pest Management, LLC. Greenleaf also uses non-chemical means, whenever possible, to eradicate an infestation. Insecticides may sometimes be necessary in order to get a serious flour beetle infestation under control, but the professionals know how to safely use these chemicals around food and food preparation equipment.