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Japanese Beetles in egg-laying mode; State trying to keep them out of Western Colorado

Beetles thrive on roses, grapes and Linden trees
Posted: 5:47 PM, Aug 10, 2018
Updated: 2018-08-11 03:00:19Z

DENVER -- Get use to the voracious little critters.

State Agricultural officials say you can't eradicate Japanese Beetles, the best you can do is try to lessen their impact.

Nita Chittivej has been trying to do that for several years now. Her rose garden has been decimated by the hungry bugs.

Chewing Noise

"Sometimes, when there's a bunch of them, you can hear the noise (they make) when they chew," she said. "It's just amazing how much this little bug can eat."

"Japanese Beetles first came to the U.S. in the early 1900s," said Laura Pottorff, the Colorado Department of Agriculture's Japanese Beetle Quarantine and Nursery Program Manager. "Colorado's infestation began in the early 90's, in Englewood."

Pottorff said the beetles came to Colorado in rootstock from the Midwest.

"The larval stages are carried in the soil," she said, "generally the root ball of the nursery stock."

Voracious Appetite

She said adult beetles feed on the leaves and flowers of 400 different plants.

"It's a huge, huge host range," she said, "which makes management very challenging."

Pottorff told Denver7 that there are pockets of infestations from Pueblo all the way to Boulder and that some have been found in Fort Collins.

"We do not have this insect on the Western Slope," she added, "and we do not want it there because peaches and grapes would be at big risk."

She added that with a quarantine, all planting material coming into Colorado from the Midwest must be certified "Japanese Beetle free."

She said it's the same for all planting material originating along the Front Range and destined for the mountains and Western Slope.

When asked what homeowners should do, Pottorff replied, "Many may not like to hear this, but tolerance is one of the first things to learn. This is an insect that is impossible for us to eradicate, so tolerance is number one."

She said there are steps homeowners can take to lessen the impact of Japanese Beetles.

Beetle Management

  • At dusk, knock them into container of soapy water
  • Replace roses with less attractive plants
  • Decrease lawn irrigation, beetles lay eggs in moist turf
  • Chemical control

Pottorff advises homeowners who use chemicals to follow instructions.

"If you apply an insecticide to a plant that is in bloom, be aware that pollinators (bees) will also be visiting that plant and they, too, are susceptible to the insecticide," she said.

She added that researchers are also looking into biological control to see if other organisms, that target beetles only, can be used in the fight against the hungry plant eater.

Beetle Traps

Pottorff said beetle traps, which use pheromones, can be used in areas where there is not an infestation, but there is new rootstock.

"It would be counter-productive," she said, "to put a trap in Denver, say at Cheesman Park. The pheromone bait would bring in literally thousands and thousands of beetles and we don't want to do that."