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Japanese beetles detected again

Japanese beetle trap
Japanese beetle trap and close-up of beetle
Japanese beetle has been detected again in North Dakota. The pest was found in 40 traps across the state in 2015.

Japanese beetle (Popillia japonicais one of the most destructive pests in landscapes. It destroys lawns, roses, grapes and more than 300 other plants.

The beetle has been in the USA for 100 years and has been found every year in North Dakota since 2012. Japanese beetle is well established in Minnesota, South Dakota and Montana—but not in North Dakota. It struggles to survive our brutally cold winters. It's hard to say, but thank goodness for our cold winters!

In North Dakota, we use traps to locate and eradicate colonies before they become established. In 2015, the North Dakota Department of Agriculture (NDDA) set up 1,700 traps to monitor for the beetle. Traps were set up across the state with a focus on high-risk areas including nurseries and irrigated golf courses.

A total of 56 beetles were caught in 40 traps located in 10 counties. These were in Barnes (1 positive trap, 1 beetle); Burleigh (12, 15); Cass (10, 14); Grand Forks (2, 2); McKenzie (1, 1); Richland (1, 1); Stark (2, 3); Stutsman (1, 1); Ward (6, 10) and Williams (4, 8).

These numbers are similar to 2014 and down from a peak of over 400 beetles detected in 2013. This downturn was largely achieved after a major nursery supplier in Minnesota implemented safeguards to reduce spreading the beetle when shipping plants across state lines.

The presence of Japanese beetle in North Dakota is a concern but its populations are extremely low. There are individual landscapes in Minnesota with beetle populations many times greater than what we have detected in our entire state.

Looking ahead, the NDDA will continue trapping albeit on a smaller scale in 2016. Anyone who sees a Japanese beetle next summer should contact the NDDA or their local Extension office immediately. The beetles are about one-half inch long, metallic green with bronze wing covers, and have distinctive white tufts along their sides.

For more information, download NDSU publication Integrated Pest Management of Japanese Beetle in North Dakota or watch the NDSU presentation Japanese Beetle in North Dakota.

Written by Tom Kalb, Extension Horticulturist, North Dakota State University. Source: Elhard, C. 2015. Japanese Beetle Survey 2015. North Dakota Department of Agriculture. Photos courtesy of Charles Elhard and Kristi

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