tiny bugs in new house.

Catch of the Week: Foreign Grain Beetles

November 15, 2019

One of our Des Moines pest control technicians visited a new home that already had a pest problem. The little bugs found were so tiny they were difficult to identify in the field. Preferred Pest’s expert gathered a sample, and after further inspection under a microscope, our entomologist identified the bug as a foreign grain beetle. Read on to find out more about this pest most homeowners don’t know much about.

What Is a Foreign Grain Beetle?

If you’re able to get close enough, you’ll notice these tiny insects are a reddish brown color, but appear to be black when you see them in plain sight. The foreign grain beetle is only about 1/10 of an inch in length, and is almost half the size of the closely related red flour beetle. Their minute size makes the foreign grain beetles difficult to spot until you have an infestation in your home, and it’s the reason most pest experts can’t give confirmation of the type of bug you’re dealing with on the spot. To give you a better idea of the size, our technician took a comparison photo of the foreign grain beetle next to a pen.

tiny bug in new house.

Despite what you might think, the foreign grain beetle doesn’t eat grains. It feeds on mold and fungi, which is why this bug is sometimes referred to as the “fungus” beetle. This bug can sometimes be found infesting grain storage bins, but it will only feed on damp and soiled grain. With this type of diet, these beetles thrive in damp environments. Once they struggle to find the moisture needed to survive, they move on to the next site.

How Do Foreign Grain Beetles Get Inside?

Foreign grain beetles are most likely to be found indoors in the late summer and fall while most of the outdoor trees and vegetation are starting to dry up. They will sometimes enter into homes through the smallest cracks and crevices to find a new wet environment to claim as their own. However, the most common way for this insect to get inside is not intentional.

Oftentimes, this insect is known as the “new house beetle” because it is frequently sealed into the walls of new homes. This happens during the building and construction process, and there are a few reasons for these accidental infestations:

  • If the wood used to build the home was left outdoors, it was likely exposed to rain before or during construction
  • Rain could have blown into the house throughout the project, bringing moisture in the house before it was “closed in”
  • There’s moisture built up from the drywall compound put over the sheetrock

All of these situations lead to excess moisture and the potential for mold build-up within the walls of a new home. Once the foreign grain beetle is sealed behind the walls, they will remain there as long as there’s enough moisture. The wood should naturally dry out, and then homeowners will start to notice these tiny insects crawling out of the walls. Luckily, the new house beetle is completely harmless - they don’t bite, sting or stain anything - so they’re purely a nuisance pest. Homeowners can simply sweep or vacuum them up if they spot a new house beetle infestation. It can be very difficult to prevent this type of pest since these beetles are so tiny, but there’s a couple things homeowners can do. Check to make sure there are no leaky pipes or excess moisture inside the home that would attract the new house beetle, and make sure to keep the moisture in your yard to a minimum.

Des Moines Pest Removal

If you notice any strange bugs inside your home or you’d like a trained entomologist to identify the insects found in your home, contact the experts at Preferred Pest Control. Call us at (515) 415-5550 or schedule an appointment online to get in touch with our Des Moines pest control company today!


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