How to Harvest Black Soldier Fly Larvae for Feed and Compost

When Are Larvae Ready?

Larvae are ready to harvest when they reach about 3/4 inch in length and their color changes from white to dark brown or black. They will also naturally migrate upward toward light, which is your cue.

Separation Methods

• Sieve method: Use a mesh sieve to separate larvae from the frass (compost residue)
• Light trap: Place a bright light above the bin — larvae will climb toward it and can be collected

Using Harvested Larvae

1. Dry them in a dehydrator or oven at low heat for storage as animal feed
2. Feed fresh to chickens, ducks, fish, or reptiles (high protein)
3. Bury directly in garden beds as a slow-release fertilizer boost

What to Do With the Frass

The remaining frass is an incredibly potent organic fertilizer. Mix it into potting soil at a 1:4 ratio or use as a top dressing around established plants.