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Purple Loosestrife Under Attack at Oaks Bottom


UPDATE: The State of Oregon Department of Agriculture has prepared a list of pertinent information regarding the current situation with biocontrols in Oaks Bottom. Please visit for additional details and contact information. 

Invasive purple loosestrife has been abundant in the Oaks Bottom Wildlife Refuge for years, as it is in wetlands across the country. Ten years ago, Environmental Services and Portland Parks and Recreation started working with the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service on biologic controls.

purple loosestrife at Oaks Bottominvasive purple loosestrife thrives in some parts of Oaks Bottom

They released leaf beetles that feed exclusively on purple loosestrife. For several years, high water in Oaks Bottom flooded the beetles in May and June before the invasive plants grew high enough to keep the insects above water.

adult leaf beetlesadult leaf beetles feeding on purple loosestrife at Oaks Bottom

In the last two summers, city staff noticed that more leaf beetles survived and consumed more purple loosestrife. This summer, it looks like they’re finally getting to eat all they want. In some areas, loosestrife plants are completely defoliated. If low water and dry conditions continue, defoliation could increase tenfold this summer.

defoliated purple loosestrifepurple loosestrife in the southwest corner of Oaks Bottom after a leaf beetle feeding frenzy

Learn more about Oaks Bottom Wildlife Refuge as well as future planning for habitat enhancement happening within the next few years. 


Add a Comment


Karen Barnack

August 9, 2015 at 12:39 PM

Yesterday afternoon, 8/8/15, swarms of small brown beetles appeared in the Westmoreland and Sellwood area, particularly along the bluff areas above Oaks Bottom. Several people have posted on Next Door about these beetles. They are in gardens, eating plants. In mine, they seem to like zucchini, green beans, and my grapes. Many folks have been consulting Portland nursery and master gardeners about how to get rid of them. What guidance can the city give us in how to deal with this invasion?


Laurie Ortega

August 9, 2015 at 12:44 PM

A very large hatch of these beetles are now infesting my neighborhood (Westmoreland) and defoliating my crepe myrtle trees.

Please let me know if there is anything I can do about this.


Jean DeVenney

August 9, 2015 at 4:58 PM

The potato vine in my window boxes and hanging plants now looks like it's been hit with a shotgun. Seems they like more than purple loosestrife. I am checking my garden vor more damage. Not happy.


Teresa Darling

August 9, 2015 at 5:27 PM

In 24 - 48 hours, my roses are being rapidly defoliated. They clearly DON'T eat purple loosestrife exclusively. Messing with mother nature ... now who knows who is spraying what and what kind of imbalance we'll face. Other people have complained about their plum trees, green beans, etc ...



August 9, 2015 at 5:56 PM

I noticed them today for the first time in my backyard. They were swarming and it was so bad, I could not be out in my backyard. They were getting in my hair, on my clothes; they were everywhere. I hope they have the lifespan of the mayfly.



August 9, 2015 at 6:09 PM

Tons of them swarming on and along the waterfront bike/pedestrian path as well. Had to stop several times while riding to brush them all off.



August 9, 2015 at 8:01 PM

These beetles are incredibly disruptive and damaging to our neighborhood. My son was in tears yesterday trying to bike through a swarm of them. They stick to your hair and clothes. I really hope someone will be addressing this issue.


Jackie Holley

August 10, 2015 at 7:36 AM

I came home Sunday night after spending the weekend in Eugene. My plants were covered in thousands of beetles, mostly on my crepe myrtles. This isn't just about having a beautiful garden, the amount of beetles was truly overwhelming. The were all over our cars and my teenage daughters saw them swarming over our yard. Quite upsetting! Hard to believe this is a coincidence to the release of beetles at Oaks Bottom.


John Buehler

August 10, 2015 at 8:27 AM

SE 18th and Rex, beetles massing on our crepe myrtle. Some of the branches are starting to look like the loosestrife "after" photos above. Tried hosing them off, in hopes of at least slowing them down. We'll see.



August 10, 2015 at 9:07 AM

On 17th and Bybee, there are swarms, hundreds inside of our house. I've been trying to vacuum them since I don't know what else to do.



August 11, 2015 at 12:15 AM

This is horrible for seniors living in older homes that don't have storm windows to keep the beetles out of the house. Saturday was hot and it was horrible that you couldn't even open a window or door to let fresh air in. I'm hoping that the life span of these beetle is short lived, but what is being done to resolve this issue? The QFC store in Westmorland had them all over inside the store.

When will this issue be addressed? The neighbors of Westmoreland and Sellwood really deserve an explanation and what we can do to rid these beetles.


Paul Boine

August 11, 2015 at 8:28 AM

Our nursery sells Many Crape Myrtles and they are widely popular and NONINVASIVE trees and shrubs. They are used as street trees in the Portland City Limits. They are members of the Lythraceae- the same as Purple Loosestrife. They are being defoliated and possibly killed by this beetle.
This could cost my small business Xera Plants Inc. thousands of dollars and rob homeowners of HUGE established trees. And shut down my business.
By the way- two other very popular members of the Lythraceae- Cuphea and Pomegranate and it appears many other non-invasive plants are affected.

This is going to cost gardeners immensely. Who did the research before this process was recklessly set in motion?

This is nothing less than a complete environmental disaster.
Paul Bonine
Xera Plants Inc.


Richard Allan

August 11, 2015 at 9:43 AM

Research conducted at Oregon State University nearly 20 years ago confirmed that these beetles do not "exclusively" eat purple loosestrife, and that they also eat crepe myrtle, which (taxonomically speaking) is a member of the same order as loosestrife:
According to the research, the beetles cannot complete their life cycle on crepe myrtle, but it is quite clear to anyone in the Sellwood and Westmoreland neighborhoods that the beetles nonetheless can defoliate a crepe myrtle tree.


Paul Bonine

August 11, 2015 at 11:17 AM

Well the. The city is liable for the damage that it has cost my business and home owners. The reports I'm getting from cusfomers is very bad. Obviously there is gross incompetence at the city. The reports are that they are eating all sorts of plants. Incompetence. Funny the city won't call me back.


Naomi's Organic Farm Supply

August 11, 2015 at 1:31 PM

We started hearing from customers this weekend, with disturbing swarms of these beetles at their houses, on them and on their plants, particularly Crape Myrtle, Roses and Pomegrantes. Yesterday on 8/9/15 they found the Crape Myrtle nursery plants at our shop and did severe defoliation damage within a few hours in the afternoon. We sprayed the plants with neem oil and quarantined them. We have not had to use any insecticides on our nursery plants in the past six years. Neem is the most organic option, but still needs to be used with care. It has the lowest toxicity when applied at night while bees are inactive. The Xerces Society has more info in this pdf -



August 11, 2015 at 4:02 PM

I live in Gladstone and 33rd, I found the beetles last night they just about killed my small Crepe Mirtle and also started festing on my dogwood. Y try Neem oil and killing them by hand.


Barbara Bernstein

August 11, 2015 at 5:07 PM

I had a very frustrating conversation yesterday with Lynn Barlow with Portland Parks and man from USDA who was with her. They were walking the neighborhood to see the damage. I was told by the USDA guy that they released the beetles in Oaks Bottom as recently as 2 years ago. They started the releases in 2005. For a short time they seemed to be killing the purple loosestrife but several years ago the loosestrife exploded with a vengeance. Mark Wilson who used to be the Parks ecologist told me back then that the beetles had trouble wintering over in Portland, they were not acclimated to our climate and would drown in the spring when the bottoms was full of water. But I learned yesterday that they continued to release the beetles hoping they would work. Last year's brood did winter over successfully because it was so warm and we had a dry spring. So successfully that they ate all the loosestrife and then headed into town. Though they are supposed to only target loosestrife, crepe myrtle and some roses when I was down in Oaks Bottom today I saw them crawling over most of the understory plants and have decimated most of the thimble berry, snow berry, bleeding hearts, piggy back plants and other natives that were planted a few years ago. They are even going after the blackberry and morning glory. It seems like the scientists and the official spokespeople really don't know what they've instigated and are not being forthcoming in taking responsibility or finding a solution. The ODA representatived lied on the news last, saying that the beetles have been effective in keeping the loosestrife down. Anyone who lives in the neighborhood knows that's not true. So how can we believe anything else they tell us?


Matthew Burlin

August 12, 2015 at 4:05 PM

Thanks everyone for your comments. The State of Oregon Department of Agriculture has prepared a list of pertinent information regarding the current situation with biocontrols in Oaks Bottom. Please visit for additional details and contact information.


Forest Kernan

August 14, 2015 at 11:31 AM

I wish I had been alerted about the danger these beetles pose to Crepe Myrtle so I could have taken action to protect my tree! As I was watering my tree last evening I discovered that it had been almost completely defoliated with masses of beetles on the last few remaining leaves. I am pretty sure my myrtle tree will die as a result and am now worried about them destroying my dogwoods. I will definitely try Neem oil tonight, thanks Rita! I alerted a neighbor this morning whose myrtle were being devoured in the hopes that they can save their trees before it is too late.


Kimie Fukuda

August 23, 2015 at 12:33 AM

We live between stark and pine and purchased two crepe myrtles at xera plants last summer. They had been growing beautifully, until two nights ago, just about to flower. Were defoliated in a matter of hours. Sure wish that there had been an advisory to protect our plants. The argument seemed to be that the beetles would avoid the need for herbicides, yet how many are now using pesticides to treat their ailing trees? This is a environmental disaster and potentially disastrous to pollinators. How will this issue be addressed?

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