Japanese Beetle

Japanese beetles, first discovered int he US in 1916 (and Minnesota in the 1990's), are serious pests to turf, some tree species (see list below) and plants. They feed on the roots and foliage of over 300 types of plants. They're active seven months out to the year, but we only seem them for about six weeks. They can be controlled with insecticides, but timing is imperative. Consult your ISA Certified Arborist® regarding your best treatment options.

The Symptoms:

  • Lace-like damage to leaves
  • Beetles visible on plant or tree
  • Damage to turf


  • In about June, the grub that has been in your soil has turned into a pupa - feeding on turf roots
  • In about late June or early July, this pupa emerges from the soil as an adult
  • Adults begin to feed on plants and trees, mate, and lay their eggs in the soil
  • The damage caused by their feeding can be seen starting when the adult emerges, late June to early July
  • In just over two months, one female Japanese beetle can lay a total of 60 eggs
  • You don't just have one beetle - because odors and pheromones are released to attract other beetles

Trees & Shrubs Affected:

  • American chestnut
  • American elm
  • American linden
  • American mountain ash
  • Apple
  • Birch
  • Black cherry
  • Cherry
  • Flowering crabapple
  • Grapes
  • Hollyhock
  • Horse chestnut
  • Norway maple
  • Plum
  • Roses
  • Walnut

Most trees do recover from Japanese beetle damage - and will usually start growing again once the beetles have stopped feeding. However, the feeding by these beetles on plants and trees that are already stressed, can take a larger toll on their overall health and vitality.

If you suspect you have Japanese Beetles, contact your ISA Certified Arborist® right away for available treatment options.


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