SIOUX CITY - A year ago Jessica Kayl didn't know much about the Japanese beetle, but this summer the Mosher's Greenhouse clerk said she has no trouble identifying the pesky metallic bugs that are chewing on the leaves of plants and trees all over Siouxland.
"They're really bad this year," said Kayl, who has fielded numerous calls from customers seeking to eradicate the insects from their gardens and lawns.
Japanese beetles are native to Japan, not Iowa, but their numbers are skyrocketing in the state. Hot and sunny weather conditions, coupled with an abundance of their favorite foods, is allowing the bugs to live and thrive in Iowa, especially this summer.
The Japanese beetle was first discovered in the United States at a New Jersey nursery in 1916. Its larvae likely entered the country through a shipment of Iris bulbs.
About five years ago the insects with shiny copper-colored bodies and green heads began making their way across the country from the East Coast. They stowed away in cars, moving boxes and plants, because they aren't the strongest fliers.
Mimi Shanahan, a horticulturist with Iowa State Extension, said the Japanese beetle's favorite things to feed on are commonly planted in Siouxland, such as rose bushes, grapes, raspberries and maple trees.
"They like to attack specific plants, that's not to say they never touch their least favorites," she said.
The beetles won't kill your prized rose bushes, according to Shanahan, but they will make their leaves look unsightly.
"They eat the leaf tissue away so it looks like a skeleton," she said.
Earl May associate manager Myles McCrea said Japanese beetles are targeting small maple trees at the Gordon Drive nursery.
"They'll attack just about everything. They're a really big problem," he said.
McCrea said he recommends using an insecticide spray called "Eight" to kill the beetles or trying to catch them in a trap.
The traps, which McCrea said have been effective at the store, use a flower and hormone to lure the beetle into a bag. Once they fall in, they can't get back out.
Getting rid of adult beetles alone won't solve the problem, according to Shanahan, because their eggs hatch over a long period of time.
After feeding in mid-summer, female Japanese beetles lay their eggs in the soil, which hatch into white grubs. The developing larvae remain in the ground for 10 months, feeding on the roots of turf grasses and seedlings. As temperatures rise, the larvae continue feeding into the spring, pupate and emerge into adults.
Shanahan said the University of Iowa doesn't recommend pheromone traps because they could actually attract more insects to the neighborhood.
She advises people to plant things in their yards and gardens that beetles don't like to eat, such as lilac, juniper, pine and Box Elder.