Fallen leaves and old wood do not pile up forever. Some living things are called decomposers. They break down dead plants and other leftovers. People call them nature's clean-up crew. Many of the crew are small bugs. Ants, flies and worms are on it too. Let's meet some of them, one by one, and see what each one eats and what it leaves behind.
Some beetles eat animal dung, which is poop, and bury it in the ground. Tunnelling dung beetles drag it underground and lay their eggs in brood balls made from it. When dung is buried in soil, its nutrients are recycled back into the soil. When it is left on top, nutrients such as nitrogen can be lost or run off. Without these beetles and other helpers, a pile of cow dung can sit in a field for a very long time and smother the grass under it.
Termites are tiny insects that eat wood. In the wild they break down old, dead wood. They help forests by breaking down fallen trees and stumps, and their nutrients go back into the soil. Termites eat the soft part of the wood grain first and leave the harder part. You may have heard that a termite digests wood all by itself. In fact, most termites cannot. Tiny one-celled living things called protists in a termite's gut help turn wood into food for the colony.
Millipedes live in damp places under old leaves and eat bits of rotting leaves. They hide under leaves, logs and stones. A pill bug, also called a roly-poly, rolls up into a tight little ball when it is bothered. You may have heard that millipedes bite people and wreck houses. In fact, they are slow and do not bite people or harm things in a home. Those that wander indoors in dry weather usually die, because a house has too little moisture and rotting leaf food for them.
Springtails are tiny and can jump. A springtail has a fork-like part folded under its body. When it lets go, the fork flicks the springtail into the air. Springtails live in soil, leaf litter and compost. They eat fungi and rotting plants. They cannot bite or sting and are harmless to people. Finding them in soil is usually a good sign, because they are signs of living, healthy soil. Springtails that come indoors in search of moisture are only temporary guests. They do not damage a home or breed in it.
Two more bugs turn leftovers into something useful. Leafcutter ants carry bits of leaves to their nest. You might think they eat the leaves, but they do not. They use the leaves to grow a fungus, and they eat the fungus. Black soldier fly larvae eat rotting food scraps. What they leave behind is good for soil. Adult black soldier flies do not bite, and they live only about six days.
In a compost pile, tiny living things and small bugs eat old leaves and food scraps and turn them into dark brown compost. A working compost pile gets warm. The heat comes from the tiny living things that are eating inside it. Decomposition happens much faster in a compost pile because the pile can be made ideal for the microbes. A pile that is too small does not get hot enough.
Earthworms live in soil and eat dead leaves and bits of soil. Their droppings are called casts. Casts hold soil, bits of plants and tiny microbes, and they feed the soil. Worms also join the work in a compost pile, where bacteria work first and their numbers jump. When the pile cools, centipedes, millipedes, sowbugs and earthworms carry on the work. Decomposers recycle nutrients from dead plants back into the soil, which helps plants grow.
Words to know
- decomposers: nature's recyclers
- nutrients: food for plants
- casts: worm droppings
- protists: tiny one-celled life
- compost: rotted plant mix
