Yellow-Spotted Millipede

We recently received five photos from a reader containing images of different caterpillars. He hopes we will identify them. We will be writing an article for each of these different organisms! This is the fourth of the caterpillar posts.

Surprise! This caterpillar is not actually a caterpillar, but a millipede! Although the creature resembles the shape and pattern of a caterpillar, we determined it to be a millipede after noticing its many legs. The creature in the photo has a hard black shell with three yellow spots on each segment, and yellow legs. What an interesting looking millipede!

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We have determined this to be a Harpaphe haydeniana, also known as the yellow-spotted millipede, almond millipede, or cyanide millipede. For simplicity, we will refer to it as the yellow-spotted millipede for the length of this post. These belong to a genus of flat-backed millipedes. Their coloring is a warning that they release toxic hydrogen cyanide as a defense mechanism. They get their other name, the almond millipede, from the almond scent they are associated with. These millipedes live on the Pacific Coast of North America, and are especially associated with redwood forests. They excel in breaking down leaf liter and freeing nutrients from it. Due to their toxicity, these millipedes don’t have many predators.

To end, we were fascinated to learn that this caterpillar was not actually a caterpillar, but a yellow-spotted millipede! It’s legs, and hard-shelled segmented body was a give away!

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Caterpillar Post 4-Yellow-Spotted Millipede
Article Name
Caterpillar Post 4-Yellow-Spotted Millipede
We recently received five photos from a reader containing images of different caterpillars, but this one is actually the yellow-spotted millipede.

1 Comment

  1. Stéphane


    Do they are harmful for the worms in the compost ?

    I have hundreds of them and I can see some enter inside worms’tunnel.

    Thanks in advance for the answer.

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