Aphids

• Aphids are small, sucking insects that can cause the leaves of mint and other plants to curl, turn yellow, then drop. Aphid species range in color from green to black. A severe infestation can kill a mint plant. Ants carry aphids to plants and feed on their excretion, so keeping ants away will help prevent aphids.
  
  

Mint Cutworm and Other Cutworms

• Several types of cutworm larvae can attack mint plants. The mint cutworm is fairly large, and is yellow, green or tan colored with black spots on its body. These worms chew on stems at ground level or just under the soil surface, causing them to turn yellow and die.
  
  

Controlling Insect Pests on Mint

• Insecticidal soap is a remedy for aphids of all types. Spray your plant every other day for one to two weeks, making sure you drench both sides of the leaves thoroughly. Cutworms are fairly large, if you dig up your mint you can remove and dispose of them. Bacillus thuringiensis (Bt) is a natural product available at nurseries that might help to control cutworms, but it has not proven effective in commercial operations.