Invasive SpeciesJapanese beetle

Popillia japonica
FOUND by JS-OceansideW
ID Confirmed
Quality checked by Me
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Field Notes
I went out to look for Japanese Beetles and found that the side of my shop was covered with Giant Knotweed that was not on this side of the shop just three years ago. I was surprised to find so much Giant Knotweed had moved from one side of the shop to the other.
Supporting Evidence
Photo of my evidence.
Many beetles on one leaf. As you can see, the leaves around this one have many holes where the beetles had been.
Photo of my evidence.
Japanese beetle on one leaf, next to another that has been skeletonized.
Photo of my evidence.
Four Japanese beetles on one small leaf with the other leaves skeletonized.
Species Observation: Species Looked For
Did you find it?: 
I think I found it
Scientific name:
Popillia japonica
Common name:
Japanese beetle
Sampling method: 
Just looking around
Photo of our sampling method.
Place Studied
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Map this species
N 43.999516 °
W -69.270276 °
Observation Site Information
A photo of our study site.
Upland - Field
Trip Information
Trip date: 
Sun, 2015-08-09 17:04
Town or city: 
Type of investigation: 
Species Survey
Eastern Coastal


We did, indeed, cook with knotweed. We cut the new shoots (very small and flexible ones). Raw, they taste a lot like rhubarb. After much trial and error I realized I should just look for rhubarb recipes and substitute knotweed. I also realized that most rhubarb recipes call for lots of sugar - something knotweed needed to become palatable to my 8th graders. It was a great day foraging for food in our woods, preparing, cooking, and then eating..something many of my students have never done. We adopted the slogan, "If you can't beat it, eat it.."!

awesome slogan :)

I found this really interesting, wondering ifJapanese beetles could have any potential to keep Japanese knotweed in check. I did a quick hunt online and found a few interesting things on biological control of knotweed:

Biocontrol could be an interesting topic around this species (as well as loosestrife and others).

People can eat it too. I think Mrs. Tate's class in Dedham made some baked goods recently from knotweed!



Fascinating articles about knotweed control with other organisms! However, I always worry that if (in some ideal scenario) the introduced organism does eat all the knotweed, then (in a not ideal scenario) we have another invasive species to deal with (the knotweed consumer). I'm always hesitant about fighting one invasive with another for this reason, though I do wonder if native species could somehow be targeted against knotweed (that said, native species can become invasive too in some cases). It's a tricky discussion but a good one to have!

I think, though, the best possible may be eating knotweed in baked goods like Mrs. Tate's class did! Maybe we need to have a Vital Signs baking party soon!? I'll bring some knotweed bread (topped with roasted and salted Japanese beetles, perhaps?).




We'll bring the autumn olive jam! Fried popcorn greencrab? Garlic mustard alfredo sauce? Rugosa Rosehip tea? Starting to sound like a meal...

Totally agree regarding biological control. The articles talk a lot about that. Determining a biological control option is super hard. They do a ton of research to make sure that the proposed organism eats only the target species. That's why Japanese beetles are bad for that. They eat EVERYTHING.

Wow, you caught one invasive eating another! Great observation and find!