Blue bottle flies, or blow flies, are a common house fly. They reproduce extremely fast, in great numbers, and are known to spread disease and contaminate food. For these reasons, they are most commonly seen as a pest, but they are a healthy food for reptiles and can serve as pollinators in a greenhouse garden.
Order blue bottle fly pupae from a local pet store or online pet supply website. This will get you a starter culture to breed them at home.
Allow the pupae culture to hatch according to the pet store instructions. Typically, this means you store the pupae in a warm area in the container they arrived in, and within 24 hours they will begin to hatch. There will be hundreds of flies once they hatch.
Prepare a mixture of 1 cup dry dog food and 1 cup milk. Allow it to sit out for a day to sour. Flies need the smell of rotten meat to lay eggs. Dog food allows you to obtain that odour without using actual rotten meat.
Put the container of hatched flies in the refrigerator to put them in a hibernation state. You can move them easily to the dog food container this way. Once they are still, pour them into the dog food container and allow them to lay eggs. The flies lay eggs almost immediately once they have a food source. Once you see eggs, put the container in the refrigerator again to put the flies into hibernation.
Replace the adult flies in their original container for use as feeders or pollinators.
Allow the eggs to hatch into maggots. The eggs hatch within 24 hours, and the maggots will feed on the dog food for about a week. Once they are finished eating, they will begin to crawl around looking for a place to pupate.
Fill the second plastic container with soil or dirt. The maggots need a place to burrow down in order to pupate. Move the maggots to the dirt using tweezers or carefully dump them in.
Give the pupae about two to three weeks to hatch into blue bottle flies. Repeat the process to culture more flies.