Feeding Black Soldier Fly Larvae to Wild Birds

Dried mealworms dominate the wild bird food aisle. For most of the year that is fine. During breeding season it is a genuine problem, and BSFL are the fix.

The Calcium Problem in Breeding Season

A laying female needs calcium for eggshells. Nestlings need it for bone. This is the period when a garden bird's calcium demand is at its highest — and mealworms are a very poor calcium source, with a calcium-to-phosphorus ratio that works against the bird rather than for it.

Birds filling up on a low-calcium supplementary food during breeding season are eating instead of foraging for what they actually need.

BSFL carry roughly 9,340 mg/kg of calcium. They are the one common insect food that supplies what the season demands.

Which Birds Take Them

Anything insectivorous or partly so: robins, bluebirds, wrens, tits and chickadees, thrushes, starlings. Bluebirds in particular are well known for taking supplementary larvae.

How to Offer Them

• An open dish or platform feeder. Dried larvae blow out of tube feeders.
• Rehydrate in warm water for a few minutes — especially in dry weather, and especially for nestlings, which get much of their water from food.
• Put out what gets eaten in a day. Wet larvae left out will spoil.
• As a supplement, not a diet. Supplementary feeding supplements.

The Nestling Warning

Never leave large dry larvae where nestlings can be fed them. A dry larva of the wrong size is a genuine choking hazard for a chick. Rehydrate during nesting season, and offer smaller grades.

See also BSFL for backyard chickens.