After six straight years of single digit detections, the Oregon Department of Agriculture has trapped 14 gypsy moths this summer including two Asian gypsy moths in the Portland area. The results signal an increased concern of the threat posed by the plant-eating invasive species and has prompted an evaluation of next steps to deal with the insect pest.
“This is an exceptionally destructive insect that would change the health of our forests, making them far more vulnerable to other invasive plant issues, causing a loss of foliage on trees as well as damaging agricultural-related industries that would face quarantines should the gypsy moth get established,” says Clint Burfitt, manager of ODA’s Insect Pest Prevention and Management Program.
[ See ODA's Gypsy Moth Fact Sheet. ]
After placing approximately 15,000 traps statewide this spring, ODA has found seven gypsy moths near Grants Pass in Josephine County, five in the greater Portland area, one in Forest Grove in Washington County, and one in West Linn in Clackamas County. Two of the moths were trapped in or near Portland’s Forest Park, another two in the St. Johns area and the Port of Portland’s Terminal 6. Perhaps most significant is the detection of Asian gypsy moth– one in Forest Park, the other near St. Johns. The other 12 moths are the more common European strain of the insect.
Asian gypsy moth is potentially a much more dangerous insect. Unlike its European cousin, the female Asian gypsy moth has the ability to fly, which could lead to a more rapid infestation and subsequent spread. The Asian gypsy moth also has a larger appetite for what grows in Oregon, including a taste for conifers. There have been just three Asian gypsy moths detected in Oregon prior to this year– a single catch in North Portland in 1991, one caught in Portland’s Forest Park in 2000, and one caught in St. Helens in 2006.
It’s notable that two of the three Asian gypsy moths trapped in Oregon were relatively in the same locations as this year’s detections. Additionally, an Asian gypsy moth has been trapped across the Columbia River near the Port of Vancouver in Washington.
The detections of Asian gypsy moth are not completely surprising since the insect pest was ultimately transported by ships arriving from Asia, particularly Russia.
“We can speculate that the moths likely came from Far East Russia as thousands of steel plates are imported from areas across the Pacific that are infested with Asian gypsy moth,” says Burfitt.
Patrols from US Customs and Border Protection as well as US Department of Agriculture’s Animal Plant Health Inspection Service (APHIS) have worked with shipping companies to inspect vessels before they arrive in Oregon and elsewhere around the country, but the chances of intercepting every potentially viable gypsy moth egg mass are challenging. It is likely that the adult moths trapped this year in the Portland Vancouver area originated from one of those egg masses.
“We are receiving an increased number of shipments into our ports from Russia, Korea, China, and Japan,” says Burfitt. “Those Asian ports are well lit and near forested areas. The Asian gypsy moths are attracted to the lights. Female moths fly onto the ships, then lay their eggs on containers and commodities. Based on the high population of moths at these Asian ports and the egg masses that have been recovered from the ships the past couple of years, there is a heightened alert nationally to be on the lookout for Asian gypsy moth.”
Oregonians have more experience with the European gypsy moth, which is usually introduced when new residents or travelers from areas of high gypsy moth populations in the eastern US unwittingly bring the pest with them on outdoor household furniture or other items that may harbor gypsy moth eggs.
For the third straight year, ODA has trapped European gypsy moths near Grants Pass and the seven detected this year are further proof of a breeding population in the area.
Now that nearly all of the 15,000 gypsy moth traps have been checked and removed for the year, ODA and its partners are examining the data while considering the best course of action. While no plans have been determined yet, there is the possibility of gypsy moth eradication projects next spring in Josephine County and North Portland. This year, the State of Washington has caught Asian gypsy moths as well, incuding the one in Vancouver.
A USDA technical working group will be offering recommendations to both states on the next steps, which may include spray projects in spring 2016 using Bacillus thuringiensis var. kurstaki (Btk)– an organically approved product and natural-occurring bacterium that targets the gypsy moth.
For many years, spraying for gypsy moth was an annual event in Oregon, but the most recent eradication project took place in 2009. Oregon’s gypsy moth history shows the cyclical nature of the insect. Prior to this year’s 14 detections, there were just four detections in 2014, two moths caught in 2013, one moth in 2012, and no detections in 2011. By contrast, more than 19,000 gypsy moths were trapped in Lane County alone in the mid-1980s. Despite the lack of moths up until this year, the threat of new introductions to Oregon is constant on an annual basis.
So far, Oregon has avoided the unsavory prospect of having to learn to live with the gypsy moth. That’s why the just-completed detection program continues to be an important tool in fighting off an unwanted invader.
“History shows that we have a very good program that finds gypsy moth populations while they are small and treatable,” says Helmuth Rogg, ODA’s Director of Plant Programs. “We have a track record of eradicating small pockets of gypsy moth in Oregon as soon as we detect them. Without a good trapping program and a safe, effective eradication program, that would not be possible.”
As officials mull over the options and contemplate what needs to happen next, history shows that the Oregon Department of Agriculture’s emphasis on early detection and rapid response to the gypsy moth threat fits well with ODA’s mission to protect the state’s natural environment and economy from the impact of an invasive species that has caused havoc in other parts of the country and the world.