top of page
  • Writer's pictureChelle Hartzer

Flours for Everyone (AKA: It's all in the name)

Yesterday was World Flour Day. Apparently, today is National French Bread Day. And we use flour to make bread so, I guess it makes sense. So to celebrate these two momentous holidays, let’s talk about pests that get into flour and bread.

The obvious one is, of course, the flour beetle. There are many types of “flour beetles” but the two most common are probably the red and the confused flour beetles. These need some type of milled product, they can’t feed on whole grains. Adults may live for three years so the damage they can do over that time, while still producing offspring that will do damage is immense. With the name “flour” beetle, it’s pretty obvious what they eat, but it’s a bit of a misnomer because they can feed and develop on a huge range of food products. (Seriously! Check it out!)

Indian meal moths are another flour/bread pest. These are tricky little beasts because while you may see the adults flying around, you still have to trace them back to the infested goods. They only live about a week as an adult, and in that time are laying up to 400 eggs. It gets better: almost 97% of those eggs hatch into larvae. Most pests have an 80% or less hatch rate. Just like the flour beetles, these will develop on a range of foods. These will get into birdseed, pet foods, nuts, dried fruits, candy, and I once found them in ground coffee. But the bread is packaged, so they can’t get into that right? Wrong! It takes an opening of 5mm for them to lay an egg and infest that nice loaf of French bread.

Sawtoothed grain beetles are the next “flour” pest. These are tolerant of lower moisture levels than other grain pests and they can feed on whole grain kernels as long as they have just the slightest scratch or break to let them in. If you thought the IMM was impressive for getting into small openings, sawtoothed grain beetles can find holes 0.5mm wide and lay their eggs there. While the scientific name (Oryzaephilus surinamensis) literally means “rice-lover from Suriname” and another common name is the malt beetle.

Warehouse beetles are a bit of a funny one because these are mostly attracted to high protein food sources. We typically don’t think of flour or bread as high in protein, but a lot of yeast is used. On top of that, research shows that a huge number of these are caught outside flour mills. By the end of the season when they have had all summer to expand their populations, it’s almost inevitable that they get into structures and set up on what they can find inside. In addition, these are super cold-tolerant. Larvae can survive more than 6 days at just over freezing temps.

That’s just a few of the more common ones. Depending on where you are located, some mills and bakeries can find high numbers of drugstore beetles, maize weevil (likely from the whole grains), rusty grain beetles, hairy fungus beetles, foreign grain beetles, and more.

So next time you get that lovely fresh baked loaf of French bread, or pick up that finely milled flour to make your own, remember what else would like to eat them. If you want to prevent these insects, we can help with that, contact us here.


bottom of page