Invasive beetles killing off Japan’s cherry, peach trees

TOKYO >> Cherry and peach trees across Japan are dying at the hands of invasive beetles, and one expert warns that in the worst-case scenario, there may be no cherry blossoms to view a few decades from now.

The first report of damage by the kubiakatsuya kamikiri (red-necked longhorn beetle) came in 2012 in Aichi Prefecture. Now, 11 prefectures have been hit, with cherry trees dying in parks and schools, as well as peach trees in orchards.

The beetle, native to China and Mongolia, was designated an invasive species in 2018. It may have arrived in Japan in wooden packing materials.

“No matter how many times we get rid of them, they just keep coming back,” said the office manager at Tatebayashi High School in Tatebayashi, Gunma Prefecture, while pointing out a tree that suffered holes in its trunk.

There were once 29 cherry trees fronting the school gate. They were popular among students and residents.

In July 2015, the trees started to die at the hands of the beetle. The school tried to fight off the bug with pesticide and covered tree trunks with protective nets. But swarms of beetles kept returning. By August, the staff was battling the bugs hands on and killed 350.

But since then, seven trees have been chopped down, and six stand dead. The remaining 16 are blooming poorly, and because large branches can suddenly fall off trunks, the school has given up. By the end of next year, all the trees will be gone.

The beetle’s high fertility and mobility make it especially threatening. While a Japanese long-horned beetle lays 100 eggs at most, the red-necked longhorn can lay more than 500 eggs and travel more than a mile by riding the wind.

With no natural enemies, its population abounds, and the fact that it prefers peach and cherry trees only exacerbates the problem. So far, there is no definitive method for eradicating the bug.

In Tatebayashi, the government is paying residents about 50 cents per beetle killed. Last year, citizens killed 6,249 beetles. Yet the number of damaged trees grew.

“If we don’t act now, we may not be able to enjoy cherry blossom viewing 20 to 30 years from now,” said Ryutaro Iwata, a specialist in forest entomology. “The central government must establish a system to forcibly cut down, crush and burn the damaged trees.”