When the garden glimmers with gold

Good day, ya’ll! As I write this it is hotter than Hades outside – 95 degrees F ambient (with a heat index of 105 degrees F), and no rain in sight! We are seriously into the DOG DAYS of summer, and the yarden is feeling it. The ornamental cherry tree that was here when we moved in is yellowing and losing leaves. The vegetable and pollinator gardens are droopy and dry each afternoon. The native plants are faring well, but even those newly planted this spring need an extra dose of water every day lately. It’s been a crazy, hot month around Pokeberry Pines.

In spite of the crazy hot weather, we are eating and drinking from our garden gifts every day now – tomatoes, cucumbers, zucchini, basil, nettles, anise hyssop, sage, sweet potato greens, and more. And as the pollinator plants and new trees and shrubs grow and flower, we are seeing more and more cool insects around.

One morning’s harvest…

A week or so ago I was inspecting our sweet potato plants, noticing that a few of the leaves had small holes chewed through them. Upon turning over a leaf, a saw a flash of glistening gold and then it flew away. I was stunned. It had looked like a tiny puddle of molten gold on the green leaf, but clearly it was some kind of flying insect. I continued to look for others and finally found a small group of three golden spots on another leaf.

I finally got lucky enough to capture a cell phone picture of a group of them and was able to identify them as Golden Tortoise Beetles (Charidotella sexpunctata bicolor), which never get larger than about 7 mm long.

Golden tortoise beetles on sweet potato leaf

When we lived in Florida we often found an irridescent green species of tortoise beetle on our saw palmetto bushes. We enjoyed finding them and loved watching them march across the leaves on their cute yellow feet, but they never flew away as quickly as these golden beetles do. So, I got curious about these new Golden Tortoise Beetles and did a little research, and now I’m totally in love with them.

First of all, if you look at the photo closely you can see that their wing coverings are domed and actually flare out a bit at the bottom, giving them that tortoise shape. Those wing coverings are also transparent at the bottom so they look like they have a glass shell covering them. When they feel threatened, they tuck all their little feet up under that “shell” and sit flat on a surface. They are so brilliantly golden that the glare off their backs confuses predators like birds.

Golden tortoise beetle with its transparent “shell” and golden coloring

Golden tortoise beetles also have the ability to rapidly change color at will, often when threatened or when copulating. They change from this metallic golden to orange-red with black spots or to brown with black spots. How does this happen? The transparent shell is made of grooved, tiered layers with a red pigment below it. When that red liquid fills the shell’s tiny nano-grooves, it causes the transparent shell to smooth out and perfectly reflect light, giving it that golden metallic sheen in bright light. When the red pigment drains from the grooves, the gold color is no longer reflected and the underlying colors of red and orange and black show up.

Golden tortoise beetle at the edge of a sweet potato leaf.

The larvae of the Golden Tortoise Beetle also have a crazy adaptation. They have what’s called an anal fork, which is a long anus that can reach over the back of the larvae. They use this anal fork to pile feces and shed skin on top of themselves, deterring predators. They can also use this pile of feces and shed skin (called a fecal shield or fecal parasol) to smack predators if they get too close! Here’s a video of a larvae building a shield. What a defense!

Golden tortoise beetles only eat plants in the Convolvulaceae family – like sweet potatoes and morning glory, but they rarely do enough damage to warrant killing them or trapping them in your garden. So, we’ll be leaving them on the sweet potatoes, watching and enjoying them through the rest of the summer and seeing if we can catch them changing colors.

What weird critters are in your garden today?

3 comments

    • I agree on the band name… And the very next day, I found a different beetle and poop-covered caterpillars on a sumac, and discovered that those caterpillars also make a fecal Sheild. Pretty awesome.

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