Japanese Beetle

Japanese beetle adult on leaf.

Japanese Beetle 

First discovered in the Denver Metro area in the early 2000s, Japanese beetle (Popillia japonica) has since moved throughout the Front Range.

Adults emerge in late-summer and feed on ornamental and agricultural plants.  The females lay eggs in the soil where the larval form overwinters.  

Adults feed on flowers, fruit, vegetables, and foliage.  They aggregate in groups to feed and to mate. The beetles are iridescent green, with tufts of white hairs along the edges of their abdomen.  They are about ½ inch long. For adult beetles, hand removal works well if done persistently.  Or use of an insecticide may be warranted.

The larvae feed on the roots of plants and are especially harmful to lawns and turf.  They are soft bodied, C-shaped, and about ¾ inch long.  Control focuses on the larval form using conventional and bio-insecticides.  

CSU Extension Fact Sheet

CDA - Japanese Beetle in CO



2023 Japanese Beetle Citizen Science Project

Landowners may enter their information to help us better understand the Japanese beetle populations along the Front Range.  

We will be using our online map to track early emergence and document the preferred Colorado hosts. 

Reporting Form


Japanese Beetle Citizen Science Project - 2022

Since 2006, Japanese beetle has spread along the Front Range and is now well established. Jeffco Invasive Species Management is supporting a statewide effort to better understand this insect’s habits. 

We launched this statewide project to track early emergence and document the preferred Colorado hosts. 

  • We received 296 reports ranging from Fort Collins to Colorado Springs
  • The majority of the reports came from northern Jefferson County
  • Roses, Virginia creeper, grapes, and raspberries were reported most often
  • The dates ranged from June 3 to Sept. 1
  • The week of August 1 had the largest number of reports (102)
  • Most sites reported observing more than 25 beetles

View our Story Map

Japanese Beetle Reporting Form - our reporting period is now closed.

  1. Invasive Species Management

    Physical Address
    700 Jefferson County Parkway, Suite 100
    Golden, CO 80401