Growing up, we would often toss our grass cuttings and food into a pile in the woods next to our house. I would watch with wonder as the food slowly shrunk away to nearly nothing. I would see all kinds of flies and beetles buzzing around the compost, but didn’t know how important they were at the time. Contrary to popular belief compost doesn’t “just happen.”
Growing up, we would often toss our grass cuttings and food into a pile in the woods next to our house. I would watch with wonder as the food slowly shrunk away to nearly nothing. I would see all kinds of flies and beetles buzzing around the compost, but didn’t know how important they were at the time. Contrary to popular belief, compost doesn’t “just happen.”
Composting is not only good for the environment, but it can create a home for many of our garden’s beneficial wildlife and can give us some healthy soil to produce beautiful flowers.
The one thing you need for a good compost heap is bugs, so I hope you aren’t too squeamish about these creepy crawlers. Even more amazing is that the bugs can tell you about the health of your compost.
The Good Bugs
The good bugs are the ones that are going to really make your compost heap shine and make your neighbours wonder how they can get soil that healthy. The insect poop, or frass, in your compost can improve plant growth and deter insect pests when applied in your garden.
Soldier Flies
When I first saw dozens of soldier flies in my compost I was worried something was wrong. It was the exact opposite. These flies, that look like wasps, are the best thing you can have to quickly break down your waste. They are basically your compost’s workhorses. In the UK they are usually a metallic colour.
When you see these wasp mimics flying around your compost, it’s because they are laying eggs. The eggs then emerge into maggots, and eventually become a dark brown to black pupae. Neither the adults or larvae bite, sting, or harm your garden.
Soldier flies break down waste that’s high in nitrogen like leafy greens, broccoli, cauliflower, lentils, and even manure into rich compost. Unlike fruit flies and house flies the adults don’t try to get into your home, and even better they actually reduce the odour rather than make it worse.
Even more amazing is that the soldier fly was recently found to be able to break down plastics in your compost! They break down the plastic into safe substances as it passes through their gut.
Springtails
Springtails are a tiny insect a few millimetres long and are very common in decaying matter. As you might expect, they literally spring into the air with a small spring-like structure under the belly that, when released, shoots them into the air. They chew on decomposing plants, pollen, grains, and fungi, and even the insect frass we mentioned.
Isopods
Isopods, known as pill bugs and woodlice are crustaceans that roll into a ball when scared, much like a hedgehog. They’re the only crustacean that has adapted to live its entire life on land.
They prefer dark, damp environments and their stomachs help transform organic matter into a finer, nutrient-rich humus that is rich in minerals and nutrients like calcium, nitrogen, potassium and magnesium.
Slugs
Slugs are often something we worry about in our garden, given their sharp teeth that can destroy the tips and shoots of our plants in just a few hours. Slugs are skilled at breaking down waste into compost. However, I am generally not a huge fan of slugs in compost as it can indicate the compost is too wet, and you run the risk of breeding the next army of garden destroyers. If you see a bunch of slugs, you can try adding more dry leaves and grasses to make the compost drier. If they have migrated into your garden, you can try a number of natural ways for controlling them.
Earthworms
We have all heard of the benefits of worms in our compost. They are quick to break down waste into rich humus because of the microbes in their gut. You may have bought worm casts from the store. These are high in available nitrogen, calcium, magnesium, phosphorus and potassium. Worms also aerate the compost by tunnelling through the waste, increasing the rate of decomposition.
Millipedes and Centipedes
Both millipedes and centipedes are blessed with dozens of legs, but outside of that they are very different.
Millipedes are often dark brown and curl up into a ball when disturbed. They love to eat decaying plant matter so are a great fit for your compost. Much like worms, they tunnel through compost. But unlike worms, they like drier conditions. A fun fact is that millipedes contain cyanide that they release in small quantities if disturbed, so don’t try to eat them!
Centipedes on the other hand are voracious predators that capture their prey and inject them with poison using modified claws. They are usually a yellow or orange color and move very fast. Depending on the size their sting can feel like a wasp if you pick them up. Centipedes do not have a waxy covering over their skin, so they need moisture to survive. Large numbers of centipedes in the compost pile often indicate that the pile is too wet.
Beetles
When you see beetles in your compost they are just there to keep your good bugs from getting out of control. They are usually predatory beetles known as rove beetles or predaceous ground beetles. They tend to hunt down your compost bugs at night, so you may see them if you are adding to your compost on a chilly winter's evening. They are also beneficial for controlling pests in your garden, so feel free to put some in a cup and add them to your garden.
Others
Pseudoscorpions look like tiny miniature scorpions, but don’t worry they won’t bite or sting you. They grab their prey with their front claws and inject poison, but not enough for us to worry about. They will eat small worms, larvae, and springtails.
Earwigs are also common in compost, and contrary to popular belief they won’t infest your ears, but they can infest your house. They are predators and also break down waste into compost.
The Bad Bugs
While an isolated “bad” bug isn’t usually a cause for concern, infestations of certain critters can have consequences for your compost. Some of them might make your compost stinky, overeat your good bugs, or even infest your garden or home.
Fruit Flies
You are probably familiar with fruit flies. They are attracted to the sweet smell of rotting fruit where they lay their eggs. They grow quickly and within a week you’ll have more adults and they keep reproducing. Though not a huge issue, you can bury fruits and vegetables at least 6 inches into the compost and cover with leaves to reduce their numbers.
Ants
Ants like to find dry soil to build their nests, so if you’re seeing ants in the pile, it’s probably a sign that your compost is too dry. Ants could eat some of the good bugs in your compost. They can also become a pest in your home as they become established. You can reduce ants by turning over your compost pile every few weeks and keeping the moisture level to that of a wrung-out sponge.
Houseflies
If you see a lot of houseflies or blowflies (metallic green or blue flies) it’s usually a sign that your compost is either too wet, or the balance of nitrogen-rich “green” matter (kitchen waste, grass clippings etc) and carbon-rich “brown” matter (drier, woodier materials like leaves and garden debris) isn’t quite right. They also commonly infest our homes or picnics, and if you know what else these flies eat, you may not be so happy to have them.
You can cover the pile or add more brown leaves to reduce their desire to use the compost pile. If you are adding meat to your pile you may want to reconsider, as it will not only attract these flies, but may attract rats and other animals.
Cockroaches
Seeing cockroaches scurry out of our compost is often enough to make us scream and worry the neighbours! While these insects are great at breaking down waste into rich compost they are not for everyone. They also will commonly come into your home where you won't want them. They love the smell of rotting food, so a well-balanced pile free of meat, grease and dairy won’t be as attractive to them.
Yellow Jackets
Yellow jackets are one of the few compost bugs that may harm you. These wasps sometimes end up making their homes in compost bins because they like to eat the insects that live there. Regularly turning the pile from early spring will prevent yellow jackets from building a nest. If you notice yellow jackets in your compost do not disturb them. Either find a professional who can remove them (without pesticides) or leave the compost pile alone until the following year, when the abandoned nest can be safely removed.
How to Deter Bad Bugs
Keeping your compost heap or bin healthy with the good bugs is the best way to deter the not so good ones. To do this:
- Regularly turn the compost and keep its level moist but not soggy
- Limit the amount of meat and dairy you add
- Regularly place a layer of brown leaves on top to balance out the amount of moisture and carbon
- Shred or break up food before adding to the pile so it's easier for the bugs to break down
Marcus Griswold
Your Bug Club
