10 Organic ways to Control Japanese Beetles: Kill, Repel, Trap

Which essential oils are most effective against the Japanese Beetle? How do I create a home made trap for Japanese Beetles? How can I kill Japanese Beetle eggs and grubs? 

1. Picking is still the best strategy for adults
Get your bucket ready. Add water and a little dish soap. Pick visible adults from leaves and branches, then drop them into the bucket. If you spot a cluster of beetles, just tap the affected branch or flower and let them fall into the bucket. If the thought of touching bugs makes you cringe, disposable plastic gloves can provide a protective barrier without reducing finger mobility. 

2. Studies show peppermint oil is the best repellent for Japanese Beetles
When 41 different oils were tested for their ability to deter Japanese beetles from powerful attractants, peppermint and wintergreen oils were found to be the two most effective. Anise, cedarleaf and bergamont mint were also shown to be quite powerful. (Source: https://www.ncbi.nlm.nih.gov/pubmed/19736768). Note that essential oils are not meant to be applied full strength. For general pest control applications, essential oils are often mixed at a ratio of two ounces per gallon. 

3. Cedar oil is known for lasting residual effects

In aromatherapy, a "top note" is defined as the first note you'll smell in a perfume blend. It comes out fighting but fades quickly. A "base note" is the lingering essence you smell when the top note is long gone. For this reason, it can be helpful to incorporate base notes into your overall pest control plan. 
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  • Common Top Notes: Orange, lemongrass, citronella, eucalyptus, peppermint, anise, sage, tea tree, thyme, spearmint. 
  • Common Base Notes: Cedar, clove, patchouli, frankincense, sandalwood.

4. ​Cedar Granules - Two months of residual effects - great for egg control

​All liquid pesticides evaporate, but cedar granules deliver a fresh blast of cedar infused liquid to the soil or grass each time it rains. The constant seepage is great for control of eggs and grubs, which feed upon the roots of turfgrasses and vegetable seedlings. Granules are great for the person who desires a pest free garden but doesn't have time to keep repeating weekly or monthly spray protocols connected to various liquid products. Granules may also be used in conjunction with liquids. Just spray your favorite liquid for an immediate punch and spread granules to keep those effects rolling for months on end.
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  • Kills all life cycles and repels fleas, ticks, ants, mosquitoes, & mites
  • Safe for plants, children and pets​
  • 20lb bag covers 5000 square feet

5. Diatomaceous Earth
​Diatomaceous earth (DE) is a powdered pesticide made of the tiny, fossilized plankton that accumulate over millennia in fresh water lakes. This moisture leeching dust causes insects to dry out by absorbing oils and fats from the exoskeleton. The sharp edges of the particles are highly abrasive, slashing at the cuticle and speeding up the process. 

Advantages: 
  • DE generally kills insects within 24 hours of contact, depending upon the thickness of the exoskeleton. Extra hearty insects with thick exoskeletons may take longer to die.
  • DE deactivates when wet but becomes effective again when it dries out. Still, it's a good idea to look at the forecast and apply on a dry day. Diatomacous Earth may be mixed with water and sprayed upon plants. 
Disadvantages:
  • Will not repel flying insects or discourage them from landing on fruits and vegetables. 
  • These sharp particles are like fiberglass when inhaled. Wear a mask if applying on a windy day.

6. ​Boric Acid - A popular additive for mixing bait
Most folks associate boric acid with the treatment of cockroaches and the mixing of bait used to attract roaches and ants, but it's also great for dusting. Beware that pets should not ingest this product. Neither humans nor pets should get it into their eyes.  Note that boric acid and Borax laundry detergent aren't the same product. Borax is the basic mineral mined from the ground. A refining process turns it into boric acid. Boric acid is more powder like. The reduced bulk and lower molecular weight promotes superior penetration into the target insect's exoskeleton. Borax for laundry is not labeled for use as a pesticide. ​When considering the compounds themselves, boric acid has a larger concentration of boron. That means boric acid is stronger than borax. Boric acid has 17.48 (https://en.wikipedia.org/wiki/Boric_acid) and Borax has 11.34% (https://en.wikipedia.org/wiki/Borax). ​​

7. ​Bait Granules - A ready-to-use product for speed and simplicity
When you don't have time to mix your own bait using ingredients like sugar, flour and boric acid, you can buy granular bait to spread throughout the garden. Granular bait works exceptionally well against ants, cockroaches, crickets, beetles earwigs, silverfish and carpenter ants! Blood feeding organisms like fleas and ticks won't be as attracted to bait as insects that constantly forage for food. For flea and tick killing agendas, stick to essential oils and follow with cedar granules. ​

8. Commercial Trap for Japanese Beetles

9. Home Made Trap for Japanese Beetles

  • Fill a clean milk jug with warm water 
  • Add one packet of yeast 
  • Add ¼ cup of sugar to the water and yeast mixture.
  • Add one mashed banana 
  • Add a squirt of dish soap to kill bugs that fall into the trap 
  • Stir to combine ingredients 
  • Place the jug near the problem area in your garden. Make sure it's slightly elevated off the ground.

10. Row Covers
An ounce of prevention is worth a pound of cure! Row covers can prevent insects from landing on your plants in the first place!