Earlier reports had pegged the number in the mid-200s. And officials expect they may find more.
Officials believe these numbers mean a breeding population had been established in the area. The pest had been detected in Portland in the prior three years, but not in those numbers. There were 25 detected in 2013, 13 in 2014 and four in 2015 — all near Portland International Airport.
Japanese beetles are a bright, metallic green with copper-colored wing covers. The grubs can be very destructive to turf, while the adults feast on a wide variety of trees, shrubs, flowers, fruits and vegetables. Growers and homeowners have been battling the bug since the first U.S. detection in 1916 at a nursery in New Jersey, where it was believed to have hitchhiked in an iris bulb shipment. It’s now present in most states east and immediately west of the Misssissippi River.
Officials are still trying to establish boundaries for the infested area so that next spring, proposed mitigation efforts can begin. Such an effort would target the grubs, which are more vulnerable.
“By the time we catch the adults in our traps, the females have mostly already mated and laid eggs in the soil,” said Dr. Helmuth Rogg, director of the Plant Protection and Conservation Programs Area at ODA. “The egg will develop into grubs in the soil that will feed a little bit before going further down in the soil escaping cold temperatures in the upcoming winter. In the spring the grub will come up and complete its life cycle and hatch out as adults in July/August of 2017.”
Potential mitigation methods would include non-hazodus products that target developing eggs and immature grubs next summer. Various options still are being considered. In the meantime one can expect an increase in Japanese beetle populations from what was seen this year.
Homeowners and growers who believe they have found the Japanese beetle are encouraged to report them to the Oregon Invasive Species Hotline at 1-866-INVADER or www.oregoninvasiveshotline.org.