Are Black Soldier Flies Harmful? Everything You Need to Know

Are Black Soldier Flies Harmful? No.

Black soldier flies (Hermetia illucens) are completely harmless to humans, pets, and homes. If you keep BSFL as feeder insects and worry about escaped larvae or emerging adult flies, this guide will put your mind at ease.

Frequently Asked Questions

Do black soldier flies bite?

No. Adult black soldier flies have reduced, non-functional mouthparts. They physically cannot bite. They also cannot sting — they have no stinger. The larvae are equally harmless and cannot bite humans or animals.

Do black soldier flies spread disease?

No. Unlike house flies that land on garbage and carry pathogens to your food, black soldier flies are not attracted to human food or kitchens. Adult BSF do not eat at all — they have no functional mouthparts. Studies have shown that BSF larvae actually reduce harmful bacteria (like salmonella and E. coli) in the material they consume.

Will they infest my house?

No. Black soldier flies cannot reproduce indoors. Adults need outdoor conditions to mate and lay eggs — specifically decomposing organic matter in a warm, humid environment. If a larva escapes your feeder container and pupates, the emerging adult fly will simply seek a way outside. It will not breed, will not eat your food, and will die within 5-8 days.

Do they look like wasps?

Adult black soldier flies resemble wasps in appearance — dark body, elongated shape, and translucent wings. This causes alarm in people who see one for the first time. But despite the resemblance, they are true flies (order Diptera), not wasps (order Hymenoptera). They have no stinger, no venom, and no aggressive behavior whatsoever.

Are BSFL safe for my reptile to eat?

Yes. BSFL are one of the safest feeder insects available. They are soft-bodied (low impaction risk), naturally high in calcium (prevents MBD), and do not bite or injure reptiles. They are fed to bearded dragons, leopard geckos, chameleons, and dozens of other species worldwide with no safety concerns.

Are BSFL safe for chickens?

Yes. BSFL are one of the most popular treats for backyard chickens. High protein and the highest calcium of any feeder support egg shell quality and overall flock health. They are widely used in commercial poultry operations as well.

Can BSFL escape their container?

BSFL cannot climb smooth surfaces. A cup or container with smooth walls contains them effectively. Prepupal larvae (the darkening stage) become more active and may crawl more vigorously, but still cannot climb smooth plastic or glass.

What if a larva pupates and a fly emerges in my house?

The fly is harmless. It will not eat your food, bite you, or reproduce indoors. Open a window or door and it will leave. Or ignore it — it will die naturally within 5-8 days. This happens rarely if you store BSFL in the refrigerator, which prevents pupation.

Are black soldier flies considered beneficial?

Yes. BSF are one of the most environmentally beneficial insects on Earth. Their larvae convert organic waste into high-quality protein and lipids, making them a cornerstone of sustainable animal feed, composting, and waste management operations globally. They reduce waste volume, suppress harmful bacteria, and produce a renewable protein source.

The Bottom Line

Black soldier flies and their larvae are safe, beneficial, and harmless. They are one of the best feeder insects available for reptiles and one of the best treats for poultry. Store BSFL in the refrigerator to prevent pupation, and enjoy the highest-calcium feeder insect in the hobby with zero safety concerns.

— Matt, Founder, All Angles Creatures