You may have heard of black soldier flies, or have some in your compost or garden. But are black soldier flies good or bad?

I believe that most insects have a role to play in the garden - even if it's that's to feed other insects and critters. With a range from garden guardian to absolute nuisance - getting to know each species of bug that visits your garden is definitely important.

When it comes to black soldier flies (BSF) and their larvae, however, they are definitely friends!

black soldier fly beneficial compost helper
Sometimes confused with wasps because of their sheer size, black soldier flies are one of your best allies in the garden and especially the compost pile

Befriend them and they'll reward you greatly

Black Soldier Fly Advantages

For gardeners there are tremendous advantages to befriending and recruiting black soldier flies to help cycle nutrients

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How Black Soldier Flies Help Compost

One of the main reasons why BSF are so beneficial to gardeners is because their larvae are incredible composters.

Everyone is familiar with worms as great composters, breaking down organic matter into rich worm castings that plants love.

Somewhat lesser-known and more effective are black soldier fly larvae, which can break down organic matter much faster than worms. Some estimates say up to 7x faster!

Black soldier fly larvae have voracious appetites and will chew through large pieces of produce in mere days. BSFL can eat twice their weight in food every day!

They also have incredibly powerful digestive enzymes, which can even break down thinks like bone and cartilage.

While worms works slowly in cooler temperatures, BSFL love the heat and can move faster and eat more in hot temperatures.

As incredibly efficient decomposers, BSFL are a valuable asset for any gardener looking to create healthy soil during the warm season!



Where I live in Arizona, that means worms make great macrodecomposers in winter, and black soldier fly larvae do the heavy lifting in summer.

black soldier fly larvae are great for compost
Black soldier fly larvae are the real champions, and eat an enormous amount of organic material rapidly building great compost

How Black Soldier Fly Larvae Reduce Food Waste

But BSF larvae aren't just good for composting. They also play an important role in reducing food waste.

In fact, BSF larvae have been used in commercial settings too. There they break down food waste and create valuable byproducts like animal feed and biodiesel.

One super common approach people take is feeding their food scraps to BSFL, then feeding the BSFL to their chickens. This is a sweet way to close the nutrient loop and keep everything cycling 'round rather than going to waste.


Black Soldier Fly Disadvantages

While these are one of the most beneficial insects you can attract to your garden, they aren't completely without any disadvantages.

It can sometimes be difficult to attract black soldier flies to your compost. They're pretty selective about where they lay their eggs, and need a moist pile of decomposing organic matter that's warm enough to lay eggs in.

You'll need to create the right conditions if you want to attract BSF's to your compost pile.

If you're struggling to attract them or aren't seeing any soldier flies showing up, you can always purchase live BSF larvae and introduce them yourself once you've got your compost conditions dialed in.

Pro Tip:

If your compost is covered or enclosed, make sure there are openings large enough for black soldier flies to get in through. They are the size of a medium wasp, and need access to the bin to lay their eggs before you'll have larvae.

Some people also find black soldier flies to be a bit scary, as they're easily confused for wasps until you learn to recognize them. With time, you can easily tell them apart.

Finally, black soldier fly larvae can be a little off-putting to folks who aren't used to watching larvae devour food scraps. Learning to love decomposition is a necessary piece of gardening though. It is the end, and also the beginning of everything ∞


Do Black Soldier Flies Bite?

Black soldier flies don't bite or sting, and they don't spread any diseases to people. They're completely harmless to humans and pets.

They also don't harm your garden, nor do they caused any damage to plants. In fact, they don't even eat!



Rather, they'll lend a hand and help your garden to thrive.


What Conditions Do Black Soldier Flies Thrive In?

Soldier flies absolutely love the heat. I often notice them show up in my compost bin once daytime temps exceeds 80F (26.6C), which is about the temperature they breed at. In warm conditions where worms often slow down, black soldier fly larvae take over macrodecomposition in compost piles.

If you rely on worms during the cool season to help with your compost, black soldier fly larva, will make the perfect companion for the warmer half of the year if you're in a hot climate.


Are Black Soldier Flies Good or Bad?

Not only are black solider flies harmless to humans and pets, but they also play an important role in composting and soil-building.


Final BSFL Thoughts...

With a little bit of effort, attracting these compost friends is definitely worth it.

BSF larvae are incredibly beneficial for composting and soil-building, and they are completely harmless to humans and pets.

Remember you can always buy the larvae live and introduce them if you're not seeing any show up on their own. Just make sure it's during the warm season and temps are 80F (26.6C)+ so that they breed and multiple in your compost.

Next time you see a black soldier fly in your garden, take a sec to appreciate all their hard work! They are busy keeping your soil healthy and turning food scraps into pure gold.