Black Soldier Fly Larvae eat most organic kitchen waste: fruit and vegetable scraps, coffee grounds, eggshells, cooked grains, bread, and similar plant-based food waste. They are not picky feeders — their digestive system handles a wide range of organic material efficiently. What they're fed matters, though, because larval diet directly affects the nutritional content of the larvae themselves.
What BSFL Eat Well
The following make up the core of a good BSFL diet and are safe to feed in regular quantities:
Fruit and vegetable scraps: The primary feedstock for most home colonies. Peels, cores, overripe fruit, vegetable trimmings — all work well. High moisture content helps, but very wet material should be balanced with drier inputs.
Coffee grounds: A reliable, consistent feedstock. BSFL process coffee grounds readily and the grounds also help regulate moisture in the bin. Used grounds from a coffee maker work fine.
Eggshells: Crushed eggshells are a calcium source. Larvae don't eat the shells directly but the calcium becomes available in the bin environment and can be absorbed. Rinse shells before adding to reduce the risk of Salmonella from raw egg residue.
Cooked grains and bread: Rice, pasta, oats, stale bread — all are processed well. These provide carbohydrates that support rapid larval growth. Don't add large quantities of bread with a lot of salt.
Spent brewing grains, pulp from juicing: Both are excellent. High in moisture and organic content, they drive fast larval growth.
What to Avoid
The following should be avoided or used only in small quantities:
Meat and fish: BSFL can technically process meat, but in a home setting it creates significant odor and increases pathogen risk. Commercial operations manage this with controlled conditions that aren't practical at home. Leave meat out of a home BSFL bin.
Large amounts of dairy: Small amounts of dairy scraps are processed without issue. Large quantities of milk, cream, or cheese create odor and may alter bin conditions in ways that stress the colony.
Citrus skin: The terpene oils in citrus peel deter BSFL feeding. Citrus flesh is fine and is eaten readily — it's specifically the skin that's the problem. If you're adding citrus, remove the peel first or add it in small quantities mixed with other material.
Heavily salted foods: Salt in large quantities stresses larvae. Small amounts from normal food waste aren't a problem, but don't dump a full container of salty chips or pretzels into the bin.
Avocado skin and pit: Contains persin, which is problematic for many animals. Avocado flesh in small quantities is generally fine, but skin and pit should be excluded.
How Diet Affects Larval Nutrition
The nutrients in what you feed your BSFL end up, in modified form, in the larvae. This is called the "you are what you eat" effect, and it's significant for feeder insect growers.
Calcium content in larvae is influenced by feedstock calcium levels. Adding crushed eggshells, oyster shell powder, or other calcium sources to the bin raises the calcium content of the larvae themselves — useful for reptile owners who want to maximize the nutritional value of their feeder insects.
Fat content varies with energy-dense inputs. A colony fed primarily fruit scraps and grains will produce leaner larvae than one fed high-fat restaurant waste. For reptile feeders, leaner larvae from a well-managed home diet are generally preferable.
Protein content remains relatively stable across different feedstocks — BSFL are efficient at synthesizing protein from diverse organic inputs.
How Much to Feed
Feed in amounts the larvae can process within 24–48 hours. Overfeeding leads to excess moisture, odor, and anaerobic conditions that stress the colony. Underfeeding slows larval growth.
A starting rule: add food roughly equal in volume to the amount of larvae present. As the colony grows, increase feeding accordingly. A mature colony in a standard home bin can process 0.5–2 pounds of food waste per day.
Moisture balance matters. BSFL need moisture to thrive, but standing water in the bin is a problem. If the bin gets too wet, add dry carbon inputs: cardboard, dry leaves, straw. If it gets too dry, add high-moisture material or a small amount of water.
Does Gut-Loading Apply to BSFL?
Gut-loading — feeding feeder insects a nutritious diet before offering them to reptiles — applies to BSFL just as it does to crickets. The key difference is that BSFL have already been consuming food continuously throughout their larval life; their gut content at harvest reflects their recent diet.
For the highest nutritional value at harvest, feed the colony high-quality varied inputs in the 48–72 hours before harvesting prepupae. A mix of vegetables and calcium-rich material in that window maximizes the nutritional profile your reptile receives.
Frequently Asked Questions
Can BSFL eat meat?
Technically yes, but it's not recommended for home colonies. Meat creates significant odor and increases pathogen risk in a home setting. Stick to plant-based food waste for home production.
Can BSFL eat citrus?
The flesh of citrus is fine. The skin of citrus fruits contains terpene oils that deter BSFL feeding. Peel citrus before adding to the bin, or add citrus skin in small quantities mixed with other material.
What's the best food for BSFL?
Varied organic kitchen waste performs best — fruit and vegetable scraps, coffee grounds, grains, eggshells. Variety in feedstock produces larvae with a broader nutritional profile than any single feedstock alone.
Do BSFL need water?
BSFL get most of their moisture from food. High-moisture feedstocks like fruit scraps are usually sufficient. In very dry conditions or with dry feedstocks, a small amount of water added to the bin helps. Don't create standing water — this causes anaerobic conditions and odor.
Can I feed BSFL only one type of food?
A colony can survive on a single feedstock, but larval nutrition and output are better with variety. A mono-diet also produces less nutritionally complete feeder insects. Vary the inputs when possible.
