Pest of the Rising Sun

Greek mythology and modern insects have more in common than you might think.

Take the Trojan War, for example. Odysseus, Diomedes, Menelaus and several dozen other Achaean warriors famously arrived in Troy late during that conflict tucked in the belly of a giant wooden horse — a trophy of sorts for the clueless Trojans — their cunning immortalized in the Aeneid. They waited only until nightfall to spring their attack and win the war. The Japanese beetle, meanwhile, though not noted for its careful martial strategy, also arrived in a foreign land — in this case, the United States — surrounded by wood, when it gained passage around the globe in a crated shipment of iris bulbs. Unlike the Achaeans, the beetle wasn’t discovered for years.

And, unfortunately for golf course superintendents, Popillia japonica seems to still be spreading, more than a century later.

The Japanese beetle long moved up and down the coast, then inland, but there were still a couple handfuls of states that remained free of their invasive destruction of various fauna, flora and fruit. That list is shorter after they arrived in Colorado around 2016.

“I had noticed in the fall that we had some yellowing in some of our rough areas, but it was also super dry, and it was near trees,” Tim Palko recalls. “I poked around and found a few grubs but nothing that was triggering for me.”

Palko is the director of grounds at Boulder Country Club. Located about 30 miles northwest of Denver, the city is considered a high desert prairie. It receives less than 21 inches of annual precipitation. And even there, the Japanese beetles have started to thrive during recent years. Palko remembers another local superintendent telling him over dinner in 2018 that the pest was so prevalent he had areas in his fairways he “could roll up like carpet.” Palko’s reaction? “Thaaaaat’s not good.”

Palko prepared for the Japanese beetles, tank mixing a popular granular insecticide with a hydrating surfactant and spraying 72 of the property’s 177 acres the next spring. He has repeated the practice every season since, often needing only a single application. “Really didn’t get any damage,” he says.

Palko has also worked with the Plant Select program at Colorado State University to replace a variety of plants around the grounds, opting less for the annuals the beetles prefer for desert plants that they tend to avoid. “We kind of switched our plants up every time we went to rebuild a bed,” he says. “That was the other way to give them less to eat.”

And while Palko has the beetles relatively under control, they still strike — and he still occasionally needs to remind members that the beetle doesn’t know it’s skeletonizing foliage on a golf course. “It just knows there’s damp topsoil,” he says, “with big, fat white roots.”