Castor Oil

• 1). Mix two tablespoons of castor oil with a few cups of water.
  
  
• 2). Place the concoction into a plastic spray bottle.
  
  
• 3). Use this as an insecticide and spray it all over the tree that is infested by the Japanese beetles.
  
  

Kill the Beetles

• 1). Fill a bucket with dish detergent and water.
  
  
• 2). Collect the beetles with your hands early in the morning when they are less active and easier to grab.
  
  
• 3). Drown the beetles in the soapy water.
  
  

Neem Oil

• 1). Purchase a product that contains Neem oil. These can be found at most home improvement stores or gardening centers.
  
  
• 2). Spray the Neem oil over the entire tree.
  
  
• 3). Respray the oil as necessary. The Neem oil will not only act as a mild insecticide to kill the Japanese beetles, it will also make the leaves on the tree less attractive as a food source for other beetles.