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Millipede the Shredder

Train your eyes: they were made to see more than you think.

Paul Coelho

I am enamored with the unloved, the small, the often unseen. The ones that scare or gross others out. I speak for them to help others at least respect them for their place on this planet. Millipedes are in that category. There at least 10,000 species of millipedes in the world and possibly eight times that number. In the Pacific Northwest there are more than 200 species. And in the last decade new species are still being found here.


Millipedes are arthropods related to insects, crustaceans, and arachnids. Centipedes and millipedes are the Myriapod family which means “many feet.” They differ from centipedes in that they have 2 sets of feet per segment while centipedes only have one set.


A walk in the moist forests from southwest British Columbia to Northwestern California may bring you to stumble upon a 2-inch yellow-spotted millipede (Harpaphe heydeniana) snuffling along in the forest duff. Observe but don’t touch! If picked up they curl up and release hydrogen cyanide which can irritate your skin and even cause lesions (not dangerous, though). Make sure you wash the area immediately if you touch them. If you get it in your eyes seek immediate medical assistance.


The scent of almonds from the cyanide permeates the area when they feel threatened. The cyanide is in too small of a dose to hurt humans but it’s an effective defense against predators such as reptiles, raccoons, spiders, snails, birds, small mammals such as shrews, and amphibians. It’s enough to kill most of the small predators. An exception are ground beetles who don’t seem to be repelled by the cyanide and munch them down. In fact, one ground beetle (Promecognathus laevissimus) specializes in eating them.


Yellow-spotted millipedes are secretive critters hiding under forest duff eating dead leaves, conifer needles, and other decaying matter. Like banana slugs, as a decomposer, they play a vital role in keeping the forest from being overrun with decaying matter. The forest floor is full of millipedes doing that vital job. So voracious are the millipedes that they eat 33 to 50 percent of all dead leaves on the forest floor!


How are more millipedes made? The male and female millipedes line up their bodies belly to belly to mate in the spring. The several hundred eggs are covered in soil and feces or stuffed down a burrow on the forest floor hidden away from predators. Some female millipedes build a tiny hut to hold the eggs while others form balls of mud with the tiny precious eggs hidden away. After 3 weeks, they emerge smaller than the adults and pale in color. After several molts they reach adult size and color.


The yellow-spotted millipede has a symbiotic relationship with a fungus that lives in its intestines. The fungus assists in breaking down the dead plant material they feed on while the millipede’s hindgut provides nutrients which the fungus absorbs. You might find tiny little pellets that look like miniature deer poop pellets under rotten logs or in leaf litter. The fecal pellets the millipedes leave behind are broken down by forest fungus then the millipedes and other small invertebrates ingest them, and the cycle starts all over again- shredding the decomposing leaf litter into smaller and smaller pieces until it becomes soil.


I enjoy just observing them puttering along on all those little legs looking for food. It’s a good reminder to stop and enjoy the moment.

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