zoology

Community Science: Japanese Beetle Survey

Community 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 100 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 is trying to determine how far the Japanese beetle has spread in Colorado and to compile a distribution map of all the records we can obtain. For this, we sought your help in the previous two years and received hundreds of samples delivered by many citizen scientists of all ages. This year, in 2019, we prepared a report to be published in a scientific journal, but a preliminary report showing most of the records on a distribution map was published by the Denver Post last year.

Staff

Frank-Thorsten Krell, PhD

Senior Curator of Entomology

Jeffrey T. Stephenson

Zoology Collections Manager


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 wing cases and green metallic front part. Below the wing cases is a row of white dots on each side. If you've found a small insect with these characteristics, you've found a Japanese beetle.

How you can help

The year 2017 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 Denver metro area. In 2018 and 2019, we want to see if the beetles invaded areas that were not affected the year before: eastern Lakewood, Wheat Ridge, Arvada, Commerce City, Thornton, and Broomfield to Loveland. While those areas were much less affected than central and southern Denver Metro, we received several records from citizen scientists. The Japanese beetle is spreading its wings. If you encounter Japanese beetles in areas not represented in the map below, 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, attention Frank Krell/Japanese Beetle Project. Attach a note with the following information:

  • the location (address) where the beetles were found;
  • when they were collected; and
  • 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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