What is This Yellow Beetle with 12 (or 11?) Black Oblong Spots Foraging on the Goldenrod?

While walking in the Rattray Marsh in October, I noticed that many of the insects were gathering pollen, or possibly nectar, from the goldenrod blossoms. There were also predators hunting there including lady beetles. While taking photos of a ladybug, I was surprised to see another beetle on the same flowerhead. This beetle was a shiny yellow green colour with 12 large black spots and long black antennae—but what kind was it?

Photo of Spotted Cucumber Beetle On NaturalCrooksDotCom

A Bit of a Pickling Problem

This was the same day that I took photos of a plant that was sporting dried spiny cucumber-like seed pods. So I had wild cucumbers on my brain when I started looking up the beetle. Just for fun, I entered “cucumber beetle” in my web search engine.

Imagine my surprise when up popped a photo of my insect! There are two varieties of the Spotted Cucumber Beetle: one with 12 spots and one with 11.

Photo of Spotted Cucumber Beetle Goldenrod On NaturalCrooksDotCom

Spotted Cucumber Beetles Eat Everything

While reading up on my discovery, I found out that Spotted Cucumber Beetles are a major pest to farmers. While in their larval stage the eat plant roots. In fact another common name for this insect, according to BugGuide.net is Corn Rootworm.

Unlike some pests, they are native and they are found throughout North America, again according to BugGuide.net.

The damage is not limited to the larval stage. As adults, Spotted Cucumber Beetles keep eating. They munch on leaves and flowers including home garden plants, according to the Texas A&M University website.

Once You Find One, You See Them Everywhere

Of course after seeing my first one at the Rattray, I then started seeing them everywhere.
I think the eye learns to find what you want it to. I’ve found when looking for Green Frogs in the swamp, spotting the first frog takes a few minutes. Then, once your eye understands what you’re looking for, you start to see them all over, under rushes, beside stumps, floating in the water, peeking out between the arrowhead leaves.

For instance, I saw another one at Riverwood Conservancy in Mississauga later that week.
Let’s hope the next one I see isn’t on our roses!

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