Why Are My BSFL Turning Black? (And What to Do)

Why Are My BSFL Turning Black?

Your BSFL are entering the prepupal stage. This is a natural part of the black soldier fly life cycle — not a sign of death or disease. As larvae mature, they stop eating, darken from cream/tan to brown and eventually black, and become harder. This is the transition phase before they pupate into adult flies.

Should You Still Feed Them to Your Reptile?

Yes — prepupal BSFL are still nutritious and safe to feed. The calcium content remains high. The main differences from lighter larvae are:

• Harder exoskeleton (still softer than mealworms or crickets)
• Less moisture content
• Some reptiles may reject the darker color or harder texture

If your reptile accepts them, feed them immediately. If it rejects them, offer to chickens or discard.

How to Prevent Darkening

Refrigerate at 50-55°F. Cold temperatures dramatically slow the prepupal transition. BSFL stored in the fridge stay in the lighter, feeding-stage larval form for 2-3 weeks. At room temperature, darkening begins within 5-7 days.

What Happens After They Turn Black?

1. Prepupa (dark brown/black): Still a larva, still edible. Feed now.
2. Pupa: Forms a hard brown shell. Not useful as a feeder.
3. Adult fly: Emerges as a harmless wasp-like fly. Cannot bite or sting. Will die within 5-8 days.

Tips

• Order amounts you can use within 2-3 weeks
• Refrigerate immediately upon arrival
• Use lighter-colored larvae first, darker ones last
• If many have darkened, feed to chickens — they eat prepupae eagerly

Shop fresh BSFL from All Angles Creatures — shipped at the optimal feeding stage with our live arrival guarantee.

— Matt, Founder, All Angles Creatures