How much thought have you given insect poop?
If you’re like most people, probably not much.
But it turns out, insect poop—known by the delightfully scientific name frass—is a hidden gem in the world of organic gardening. Tiny, unassuming, and usually hiding in plain sight, frass is packed with plant-boosting potential that your garden will absolutely love.
So yes, bugs poop. And yes, your plants want it.
What Exactly Is Insect Frass?
The word frass comes from a 19th-century German term meaning “to devour like a beast”—and it’s not hard to see why. Just picture a hungry caterpillar mowing through your lettuce leaves.
Frass is essentially the waste left behind after plant-eating insects do their thing. Unlike bat guano or worm castings, which often contain a mix of food sources, frass comes entirely from chewed-up plants. That means when you return it to the soil, you’re creating a beautifully closed-loop system: plants feeding plants through the digestive magic of bugs.
Depending on the type of insect, frass can be dry and pellet-like or moist and crumbly. Either way, it’s loaded with organic nutrients and beneficial microbes—making it a powerful tool for soil health and plant resilience.
Where Does Frass Come From?
Frass can come from all sorts of plant-loving insects—crickets, mealworms, black soldier fly larvae, and more. While some gardeners raise their own insects and collect frass directly, most frass on the market is a byproduct of insect farming. These farms often grow bugs for animal feed, and frass is a sustainable, nutrient-rich side effect of that process.
Because it’s so versatile, you may see it labeled under different names depending on the insect source—like “cricket poo,” “mealworm castings,” or simply “insect frass.”
Why Gardeners Are Falling in Love with Frass
Even though insect frass doesn’t have sky-high NPK numbers like some manures, its benefits go way beyond basic fertilization.
Here’s what makes frass so special:
- Mild, Balanced Nutrition: Frass contains a gentle mix of nitrogen, phosphorus, potassium, and micronutrients, making it safe for all stages of plant growth—even delicate seedlings.
- Microbial Magic: It’s full of beneficial microbes and fungi from insect digestive systems, helping to enrich soil biology and support healthy root systems.
- Soil Structure Boost: When added to your soil or compost, frass helps improve texture, aeration, and water retention.
- No Harm to Helpers: It doesn’t harm beneficial insects, pollinators, or microbes—so your garden’s ecosystem stays in balance.
- Chitin Power: Frass is one of the few plant-based sources of chitin—a natural compound that activates your plants’ immune systems (more on that below).
Let’s Talk About Chitin
Chitin (pronounced kai-tin) is a natural substance found in the exoskeletons of insects and the shells of crustaceans. When plants detect chitin in their soil, they react defensively—strengthening their cell walls, activating immune responses, and producing compounds that deter pests and pathogens.
Think of it like a workout for your plants. Chitin doesn’t kill pests—it just trains your plants to be more pest-resistant, disease-resilient, and overall tougher.
And because insect frass naturally contains tiny bits of chitin, it’s one of the simplest and most effective ways to deliver this benefit to your garden.
How to Use Insect Frass in Your Garden
Frass is incredibly easy to work with, and there’s no “wrong” way to apply it—just a few best practices to keep in mind.
For Raised Beds or In-Ground Gardens
- Mix 1 pound of frass into every 20 square feet of soil.
- Work it into the top 4–6 inches before planting.
- Water it in well to activate the microbes.
- Top dress with a sprinkle every 2–3 weeks during the growing season for ongoing benefits.
For Potted Plants
- Mix 1 cup of frass per cubic foot of potting soil before planting.
- Or, sprinkle 1–2 tablespoons on top of the soil every few weeks as a gentle booster.
For Frass Tea (Root Drench)
- Add ½ cup of frass to 1 gallon of dechlorinated water.
- Let it steep for 1–2 hours, then pour around the base of your plants.
- Use within 24–48 hours (or refrigerate for up to a week).
Tips for Getting the Most Out of Frass
- It’s Not a Pesticide: While it supports natural plant immunity, frass doesn’t kill pests directly—so it won’t harm beneficial bugs, pollinators, or earthworms.
- Frass May Include Exoskeleton Bits: You might notice shiny gold or black flakes—that’s just insect shell, and it’s totally safe (and beneficial) for your soil.
- Safe for Hydroponics (With Prep): You can use frass in hydroponic setups by brewing a tea and filtering out solids before adding it to your system.
- Focus on Chitin? Use Less: If your main goal is to stimulate your plants’ immune response, you don’t need much. Even 1 tablespoon per gallon of water can do the trick.
Final Thoughts: The Tiny Power of Bug Poop
It’s easy to overlook something as small and unassuming as insect frass. But for organic gardeners, it’s an absolute treasure—offering natural nutrients, soil-enhancing microbes, and chitin-driven plant resilience, all in one tidy package.
So next time you’re planning your garden amendments, consider giving insect frass a try. Because when it comes to growing strong, healthy plants—sometimes, nature’s messiest leftovers are the most powerful.