Sep 7, 2012 – Crop Mounds, Not Circles

QUESTION:

Dirt mounds are popping up in the yard. Grayish colored, almost BB sized dirt. What would cause this?

ANSWER:

My best guess would be earthworms. While we think of them as subterranean animals they commonly come to the surface to either escape overwatering and saturated soils or to migrate, and I have read that quite often when we find the worms squirming over a sidewalk or driveway it is because they chose to go there in an effort to relocate. Unfortunately, once the sun comes out they don't do so well. 

The earthworm has a hardened area on its head that it uses like a shovel to did through or into the soil, and as they emerge from the soil they do push up little earth mounds that look like a bunch of tiny round balls stuck together. Many other small critters also can make soil mounds on the surface, including burrowing bees and wasps, Green June Beetle adults, etc. But, these are going to be just little piles of dirt, often with a hole in the middle leading down to the chambers below, and generally not composed of the little BB sized balls that you describe. 

The best course of action is to ignore this and appreciate the work the worms do. If the soil piles are objectionable to the customer they can quickly be raked over and eliminated, and the free soil aeration accepted. 


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