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Citizen Science: Japanese Beetle Survey

Many of you might have seen pretty shiny brown and metallic beetles in yards and parks feeding in numbers on roses, Virginia creeper or almost any other plant you can think of. These are Japanese Beetles (Popillia japonica), a species of scarab beetle accidentally introduced to the eastern United States over hundred years ago. In the early 1990s they arrived in the Denver area, and for the last few years became a serious pest of ornamental plants and lawns. The adult beetles feed on hundreds of species of plants, preferring roses and vines. The larvae feed on the roots of well-watered lawn.


The Museum Project

The Museum is looking to determine how far the Japanese Beetle has spread in Colorado and compile a distribution map of all the records we can get a hold of. For this we need the help of as many of you Citizen Scientists as possible. 


How to identify a Japanese Beetle

All beetles look the same right? Not quite so. The Japanese Beetle is about 3/8” (8-11 mm) long with brownish/copper colored wingcases and green metallic front part. Below the wing cases is a row of white dots on each side. If you're found a small insect with these characteristics, you've found a Japanese Beetle.


How you can help

Last year was amazing: 215 Citizen Scientists brought in 2,235 specimens, from Boulder to Pueblo, enabling us to produce a comprehensive distribution map of the beetle for the Metro area. This year, we would like to see if the beetles invaded areas that were not affected last year: eastern Lakewood, Wheat Ridge, Arvada, Commerce City, Thornton, and Broomfield to Loveland. If you live there, or somewhere where Japanese Beetles are newly arriving in 2018, please collect a few and bring them to the Museum. They can come dead or alive in a sealed container or plastic bag. The preferred storage is in 70% rubbing alcohol in a tight container. Please bring them to the security desk at the Staff and Volunteer Entrance, attn. Frank Krell/Japanese Beetle Project, and attach a note with:

  • the location (address) where the beetles were found
  • when they were collected
  • who collected them.

Thank you again for your invaluable help! This is a project that could not be done without your support.

We will update the online distribution map and our online database with your records soon after they arrive.

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