Every gardener and kid is probably familiar with the earthworm. These wiggly little creatures are fascinating for both adults and children. While we generally assume earthworms are good for the soil, they can also have a dark side. There’s more to the story than simply “more earthworms are better.” Teach your kids about earthworms, telling a deeper story about their history and explaining how they can be helpful or harmful to the soil.


Explain to your kids that earthworms are not native to North America. In fact, before the European settlers came to these shores, there were no earthworms. They were all killed during the last ice age eleven thousand years ago.

Have your kids dig in the garden to find a selection of earthworms. Explain that different species of earthworms may be found at different levels: near the surface in leaf matter, in the top few inches of the soil, or deeper in the soil. Explain that there are hundreds of types of earthworms around the world.

Ask your kids why earthworms would be good or bad for the soil. In a cultivated garden, they are good. Earthworms eat up organic matter and leave droppings that help plants grow better. They create water and air channels for plant roots to grow quickly. On the reverse side, earthworms can harm forest soils. Explain to your kids that forest soils tend to be high in organic matter that decomposes slowly. This process protects tree roots and creates a fungus-rich environment trees love. Earthworms, however, come in and chew up the organic matter quickly, reducing the organic matter and fungus that the trees need for proper growth. Explain that some new species of earthworms from Asia have been wreaking havoc in forests around the country for this reason.

If you are composting or have a worm bin indoors, explain that those worms (usually red wigglers) should be contained to that pile or containers and not allowed to be released into the native environment, where they might harm the native soils.