Japanese beetles usually feed on basil plants on warm, sunny days.
Japanese beetles usually feed on basil plants on warm, sunny days.

Japanese beetles feed on plant foliage. They’re a metallic green color with copper wings and are approximately 1/2 inch long. They typically appear and begin feeding on plants during the early summer. Most of the damage they cause is aesthetic, and the plants are left with small holes throughout the leaves. Basil (Ocimum basilicum) is an annual that grows in U.S. Department of Agriculture plant hardiness zones 9 through 11, and it’s particularly susceptible to Japanese beetle infestations. Deal with Japanese beetles on basil plants when you first see them to prevent damage to the leaves and to limit future infestations.

Step 1

Hand pick Japanese beetles from basil plants and place them in a container filled with rubbing alcohol or water containing a few drops of dish detergent. You can also knock them off the plant and catch them in the container. Do this in the evening because the beetles are docile then and typically won’t fly away when they are disturbed.

Step 2

Spray basil plants thoroughly with insecticidal soap, neem oil or azadirachtin-containing insecticide once a week in the early evening until the Japanese beetles are gone. Concentrate the spray wherever the largest concentration of beetles is located.

Step 3

Cover the basil plants with lightweight, spun polyester row covers. Drape one directly over the plant or insert a wire cage into the ground around the plant and cover it to ground level with the row cover. Window screening, netting and mesh are all suitable for use as well.

Step 4

Control Japanese beetle grubs in your soil to break the beetles’ life cycle after treating your basil plant. Reduce watering as much as your basil plants can tolerate to dry out the soil, making the dirt less hospitable to the grubs and eggs. Apply a treatment of milky spore bacteria (Bacillus popilliae)–available at many garden stores and nurseries–to the dirt according to the bottle’s directions, as spore count varies by product. The bacteria kill the beetle grubs.

Things You Will Need

  • Container
  • Rubbing alcohol
  • Dish detergent
  • Insecticidal soap, neem oil or azadirachtin-containing insecticide
  • Spun polyester row cover, window screening, netting or mesh
  • Wire plant cage


  • Wash basil leaves thoroughly before eating, especially after using insecticides.
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