Insects in the Landscape: Decomposers of Organic Matter

Nathan Riggs

The final installment in our four-part series on the insect roles in the landscape will cover a topic that isn’t necessarily recognized as a role that insects play – breaking down organic matter and facilitating its return to the soil as nutrients. Sure, we think of fungi and bacteria that grow on dead trees and plants and break them down, but insects help with this, too!

Some of the more common insect decomposers include rhinoceros beetles, termites and flies.

  • How many times have you turned a compost pile or opened a rotting tree and found giant grub worms inside? Those are rhinoceros beetle larvae. In the San Antonio area, they feed on decomposing organic material in the soil for two years, including plant materials, animal manure and rotting wood. They grow to more than three inches in length and the diameter of a thumb – certainly enough to startle any gardener. Rhino beetles are related to the damaging June beetle whose larvae (white grubs) feed on grass roots, but rhino beetle grubs are much larger and completely harmless to any landscape or garden plants and trees. They make great fish bait, too!
  • For those whose homes have been damaged by termites, you’re probably viewing this entry with some level of disdain or disbelief that termites can actually be beneficial. With the help of microorganisms in their guts, termites digest wood and cellulose in the soil, materials that usually take many years to decompose naturally. Termites usually get into homes because of a trail of moisture from the home that leads them to wet wood in the home.
  • Can you imagine a world knee-deep in animal manure or the remains of animal carcasses? Probably not, thanks to one tiny, but very effective decomposer:  the fly. Blow flies, house flies and soldier flies lay their eggs on manure and animal carcasses, and their offspring, called maggots, serve to consume and reduce these materials to nothing more than nutrients in the soil. It’s all part of the natural cycle of life.

There are many other creatures  — some that aren’t insects — that help decompose organic matter in the soil that deserve some time in the spotlight, including pill bugs, dung beetles and earthworms.  Feel free to research these on your own.

I hope these articles have increased your awareness of insects as more than creatures to hate or fear, but rather to appreciate for all of the ways they enrich our gardens and landscapes.

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