Make a Beetle Bank

(By Laura Keir, Communications Coordinator)

This summer, my 8-year-old son has found lots of interesting beetles in the wild. On a hike, he spots a large black beetle on the trail and we marvel at the long antennae. “Be careful not to step on it!” he warns other hikers.

Not only are beetles fascinating creatures, they help reduce the number of pest bugs in garden beds and farm fields. Ground beetles hide in grasses or under rocks during the day, and at night they emerge to feed on insects like slugs, snails, mites, earwigs, cutworms, and aphids. While we humans are sleeping, beetles prey on pests that would otherwise eat our crops.

You can encourage beetles in your garden or farm fields by creating a “beetle bank,” and early fall is  the perfect time of year to get one started. A beetle bank is a raised area planted with native grasses, which allows beetles to take shelter during the day and then move out to feed on other insects in the fields at night. 

Make a beetle bank on your farm by following these steps.

The exact dimensions and specifications for the beetle bank will depend on the conditions at your farm. Use these general guidelines, and adapt for your land:

  1. Prepare the area by weeding, focusing on removal of perennial plants. 
  2. Use two-directional plowing or a bed shaper to form a berm that’s between 2 and 8 feet wide, at least 4 to 6 inches high, and runs the length of a crop row. If you have a large field, you’ll want roughly one beetle bank for every 50 acres, located near the center of the field.
  3. Seed the berm with a mix of perennial native grasses at about 5 pounds per 1,000 square feet. Use fescue, bent grass, and at least 30% bunch grasses.
  4. Water regularly, mow the grasses once or twice a year for the first few years, and keep it weeded. After the grasses are well established, sit back and let the beetles do their work!

If you have a garden at home, you can adapt these methods to make a smaller beetle bank. 

Rather than creating a large berm, make a raised circular area in your yard that’s at least 4 feet across. Be sure to keep this area of the yard undisturbed so the grasses can establish and the ground beetles can use their habitat.

Ready to give it a try? Post a photo of your beetle bank on Facebook and tag NCAP using so we can show our followers!

Sources for additional information:

Invest in a beetle bank by Jessica Walliser, Savvy Gardening

Building beetle banks, East Multnomah Soil & Water Conservation District

Beetle banks, Farm Wildlife

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