Soap Flush Test for Pests (like Fall Armyworms)

How to Perform the Soap Flush Test for Insect Pests in Lawns

A soap flush is a mixture of 3 tablespoons of liquid dish soap with 1 gallon of water. We find that lemon-scented dish soap is the most effective. 

Pour the mixture into a 3' x 3' area and watch the action. The soap will agitate the caterpillars' skin and they will come to the surface - you can see them and then you will know to treat for them immediately.

This soap flush test works to find fall armyworms and many other destructive lawn insect pests.

Soap Flush Test Recipe

  • 3 tablespoons liquid dish soap (lemon scented)
  • 1 gallon of water
  • bucket or large container

If the soap flush doesn't flush out any insects or caterpillars, try it again under different circumstances such as :

  • Try a different time of day
  • If you did the test in an area with damage, they may already be gone from that area, so try again along the border of the damage

🐛 If you have fall armyworms, read our article focusing on what to do about them: Fall Armyworms in Lawns. We recommend scouting for fall armyworms from July until the first frost in autumn.

This is an example of what you'll see in the soap flush test: armyworms will come to the surface so you can verify that you have an infestation.armyworm soap flush Caleb Kearney


Case Study on Soap Flush Test for Insects

Mark in Georgia purchased 2 pallets of Bermuda on August 17th. On September 12th we discovered Mark had fall armyworms. To confirm that was the problem, he performed the Soap Flush Test we recommend.

The test was positive, so he applied armyworm insecticide, and this is what it looks like now! Mark stated that “Your tip on the army worms was a lifesaver! I showed the pics to several people and they also never knew about those armyworms (and how to test for them!)”

Damage caused by fall armyworms.Fall-Army-worm-damage-e1476810838894-1
Full recovery after treating for fall armyworms.fall-army-worm-recovery-e1476810851831-1

We are here to help you if you have any questions about the soap flush test or diagnosis or treatment of lawn insects and pests. Leave your comments below and check back for the answers!


Soap flush test for insects fall armyworm