Cox Island Conundrum

Every now and then, there is good news in the fight against invasive species. Recently, I received an email including this: “Good news -- I am very happy to report that we have successfully covered all the known patches of Spartina on Cox Island this year as promised.

This is good news – I’m crossing my fingers in the hopes that we’re getting closer to solving a major problem, but I’m not breaking out the champagne just yet. Here is the rest of the story.

 About 1940, saltmarsh cordgrass (Spartina patens) was introduced to Cox Island in the Siuslaw estuary. For decades, no one paid any attention to this East coast native. Then in the 1990s, people began to notice that other non-native saltmarsh cordgrass species were becoming invasive on the West Coast. Natural mud flats in California and Washington were being converted to saltmarsh meadows. Shorebirds and crustaceans that depend on mud flats were declining.

           In 2003, experts at Portland State University (PSU) developed an Oregon Spartina Response Plan to keep Oregon free of invasive saltmarsh cordgrasses. Four species of cordgrasses were recognized as A-rated weeds (highest priority for exclusion/eradication), including S. patens. In the years since, small infestations have been found and eradicated by the Oregon Department of Agriuculture (ODA) and PSU cooperators in Youngs Bay, Coos Bay, and near the mouth of the Siuslaw River. The S. patens infestation on Cox Island was the sole blot on an otherwise perfect record.

           Cox Island posed a conundrum for ODA and the State Weed Board. The Nature Conservancy (TNC) owns Cox Island, and the preserve manager refused to allow herbicides to be used on the property. Instead, she offered to cover the cordgrass patches with black plastic landscape fabric. Over a several year period, progress in killing the saltmarsh cordgrass was slow, and the cost was high. TNC applied for lottery-funded grants (Oregon Watershed Enhancement Board(OWEB)/State Weed Board) to cover the cost.  The State Weed Board struggled with the desire to see the job carried through to the end while being good stewards of public funds. Is it right to use public funds on a non-chemical noxious weed eradication project, if the same result could be obtained quicker, more reliably, and for less money with herbicides?

           One could argue that herbicides have negative environmental impacts that should be considered.  True, though modern formulations are more specific and less persistent in the environment than older products, and black plastic isn’t exactly environmentally benign.  I’d bet that spot spraying with Imazapyr kills fewer non-target organisms over a shorter time than covering patches of ground with black plastic for a year.  In the end the State Weed Board withdrew their support for the plastic covering process.  TNC still refused to use herbicides, found other funding, and continued with the plastic.

            Even folks that are not fans of herbicides should understand that eradicating an invasive species before it spreads all over the place preserves environmental health and reduces the need for future control. Like your grandmother told you, an ounce of prevention is worth a pound of cure.

            Cross your fingers that the black plastic works and Oregon will soon be free of mature seed-producing saltmarsh cordgrass. The next challenge will be to stay vigilant until the seed bank on Cox Island is exhausted. That could take years. The really good news will come when there are no more seedlings coming up -- that’s when we should break out the champagne!

Dan Hilburn

A Second Look at Giant Reed and Brown Marmorated Stink Bug

When a new pest or weed shows up in Oregon, some agency has to decide whether to fight back or not. Sometimes we pull out all the stops and attempt eradication/containment (gypsy moth, kudzu, Japanese beetle); sometimes it is not worth worrying about or not a good use of scarce funds (European paper wasp, rusty crayfish, pavement ant). In recent years, we’ve used pest risk assessments to help better inform the decision makers. 

Recently, two species that the Oregon Department of Agriculture (ODA) put in the “not worth worrying about” category have come back to our attention, and we’re giving them a second look. They are giant reed (Arundo donax) and brown marmorated stink bug (Halyomorpha halys).

Giant reed is a noxious weed in tropical and warm temperate areas around the globe. It is a real problem in California, especially along rivers. You can buy it here in Oregon as an ornamental, and we’ve never seen it become feral. My wife planted a variegated variety in a corner of my yard a few years ago. It never flowered and didn’t act invasive. Test plots in Prosser, Washington have produced impressive yields and no evidence of invasiveness.  Apparently the fuel made from giant reed has more British Thermal Units (BTUs) than coal.

ODA did a pest risk assessment on giant reed in 2007. The conclusion was that giant reed should be placed on our Watch List, but didn’t warrant listing as a noxious weed. We’re north of its expected potential range. As a result of that report, giant reed was removed from Oregon’s official state noxious weed list and the Oregon Invasive Species Council’s list of 100 Most Dangerous Invaders.

So what’s the problem? Maybe there isn’t one, but PGE is looking into planting many of thousands of acres of giant reed around Boardman to provide an alternate fuel for their coal-fired power plant. It is an intriguing idea, but such large plantings were never contemplated during the risk assessment process. Converting a coal plant to a sustainable, locally grown fuel would be a good thing – unless it escapes, adapts, and becomes a noxious weed ala California. It is time for us to take another look. 

Ditto for brown marmorated stink bug. This Asian pest was discovered first in Pennsylvania (1996) and has now spread to at least 15 other states. It showed up in southeast Portland in 2004 and has been spreading in Oregon ever since. This fall, for the first time, it is not hard to find in Salem.  Specimens have also been found in Sandy, Aurora, and McMinnville. When it first arrived in the United States, officials decided not to try to eradicate brown marmorated stink bug. The three major reasons for this decision were: no detection trap existed, stink bugs are difficult to kill even with chemical pesticides, and the public backlash to wide-area pesticide spraying in residential areas would have been considerable. We may regret that decision.

Up until now the biggest complaint we’d heard about brown marmorated stink bug anywhere in the country was that it liked to overwinter in houses. Quite suddenly this fall, farmers in the mid-Atlantic states have noticed high numbers and considerable crop damage to a wide variety of fruits and vegetables. Homeowners are also complaining about extremely high numbers crawling on and into their houses. This is not a good sign for Oregon. In a year or two or three, we could be in the same boat.

We’re already wondering if our counterparts in Pennsylvania made the right decision not to fight back when brown marorated stink bug was first discovered and in turn if we made the right decision here in Oregon. Stay tuned for more on these two newcomers.

Dan Hilburn

Invasive Species Under Your Nose - European Earwig

Do you stop to smell the roses? If you do, you’ve no doubt met a common invasive insect, the European earwig. They love to hide in roses and other nooks and crannies that offer shelter and high humidity.  At my house they like my hose reel.  I even saw some on the roof recently while I was cleaning off moss.

There are no native earwigs in Oregon; if you see one, it’s an invader.  By far the most common is the European earwig, Forficula auricularia L.  Earwigs are omnivores, occasionally becoming minor pests.  Mostly they are just a nuisance or to the entomologically inclined, a curiosity.

I’ve had a soft spot for earwigs since encountering very large maritime earwigs while processing seaweed in a previous job on the East Coast.  Like all earwigs, they have prominent cerci (forceps) at their tail end. Interestingly in this species, the cerci are curved and asymmetrical in the male and straight in the female.

Cerci, used for mating and defense, are not the only odd thing about earwigs.  Here is some more earwig trivia: Unlike other insects, the mothers stick around and protect their young after they hatch.  Though they appear wingless, many species can fly; their wings are folded up under small wing covers on their thorax.  Earwigs are an ancient group; they were crawling around under the noses of dinosaurs.

Oregon has a very interesting history with earwigs.  In the 1920s and 1930s, Oregon State Agricultural Experiment Station, State Board of Horticulture, Bureau of Entomology, City of Portland, and Multnomah County cooperated on earwig surveys and releases of biological control agents.  For a while, Portland even had a City Earwig Commissioner!

Here is an excerpt from a 1930 report: “A brief survey was made to determine if European earwigs were present in all parts of Portland, except in the main business district.  This survey was conducted by placing tar paper bands on trees and the relative number of earwigs found under each tar paper band was noted.  It was found that earwigs were present in every section of the city in large numbers.”1

It would be interesting to repeat the survey now.  Perhaps the parasites introduced way back then are the reason European earwigs are not a serious problem now.  To my knowledge, no one has followed up in the 90 years since.  Anyone know a student in search of an interesting science project?

Another interesting project would be to survey for the maritime earwig.  They have been introduced and become established in both California and British Columbia.  If they aren’t in Oregon yet, they probably will be soon.  Keep your eyes open next time you’re at the coast, you could be the first to report this exotic species!

Earwigs are an example of an invasive species right under your nose, but don’t worry about them crawling in your ears – that’s an old wives tale!

Dan Hilburn


¹D.C. Mote.  1931. The Introduction of the Tachinid Parasites of the European Earwig in Oregon.  J. Econ. Ent. 24: 948-956.