Key Technical Points and Rearing Methods for Housefly Culture Explained

The housefly is a troublesome sanitary pest, but under certain conditions and with human control, rearing fly larvae as a high-quality animal protein feed turns waste into treasure and harm into benefit. It can effectively alleviate the two major problems currently troubling the livestock industry: the shortage of protein feed and pollution from livestock and poultry manure. It can both use livestock and poultry manure to produce high-quality animal protein feed and, after biological treatment of the manure by fly larvae, turn it into high-quality organic fertilizer.

1. Good breeds. The oriental subspecies is used for artificial rearing. The primary insect source for artificial rearing is mainly the collection of pupae. The collected pupae are placed directly into the breeder fly feed, and they begin to emerge in about 3 to 4 days. From the 5th day onward, adult flies begin to lay eggs in plastic boxes. At this time, feed must be provided once each in the morning, noon, and evening every day. Generally, houseflies lay eggs between 8:00 and 14:00 each day, so the egg-laying pattern must be understood, eggs collected in time, and larvae rearing carried out. A breeder fly can lay eggs 5 to 6 times in its lifetime, and after about 7 to 10 days it begins to age. At this point, the fly cage can be treated with boiling water to kill all the aged breeder flies, and then new breeder flies can be put in.

2. Nutrition and feed. (1) The feed ingredients for breeder flies are: milk powder and brown sugar. For every 10,000 flies, use 5 grams of milk powder and 5 grams of sugar per day. Boil an appropriate amount of water, and after cooling, put it into a small basin, with a few straws placed in it for the breeder flies to lick and suck. Use another deeper small basin or bowl, filled with wheat bran or rice bran at 70% water content, placed inside the cage for the breeder flies to lay eggs. Under conditions of 24 to 33°C, each female breeder fly lays about 100 eggs per batch, and the eggs are in clumps. Every day, take out the bran and rice bran material containing eggs from the fly cage and place it on the larvae-rearing material to hatch.

(2) Breeder fly feed: saccharified starch can be used. Generally, use 12% flour, add 80% water, mix well and boil into a paste. After leaving it to cool, add 8% saccharification starter, place it in a 60°C constant-temperature cabinet, and saccharify for 8 hours. Then take it out and add 1% blood meal and fly larvae meal or yellow mealworm meal, and it is ready.

Housefly larvae can utilize various organic materials, and larvae-rearing material with a chicken manure to pig manure ratio of 1:2 gives relatively good results. Generally, keep the material about 7 to 10 cm thick, with relative humidity of about 70% to 80%. Under conditions of 18 to 33°C, larvae can hatch after 3 to 32 hours. After 4 to 5 days, once the larvae have fed on the larvae-rearing material and grown to the stage before pupation, they can be harvested. Using a combined rearing model of yellow mealworms (insect frass sand) and houseflies can efficiently process and convert crop straw resources.

3. Equipment and facilities. (1) Extensive flat-ground rearing: mix fermented chicken manure, pig manure, or food factory by-products (such as distillers' grains, soy sauce residue, vinegar residue, etc.) and slaughterhouse by-products, spread the mixture flat on the ground, and attract natural flies to lay eggs on it. Generally, every kilogram of material can yield 200 to 250 grams of fly larvae within 7 to 10 days.

The key to using this method is to harvest the fly larvae in time and use the harvested fly larvae promptly to feed frogs such as bullfrogs and forest frogs, fish, and so on; or place them together with the fly larvae culture material into a sieve, hang the sieve above a container, or hang it 30 cm above the water surface in places such as frog ponds, and use the fly larvae's light-avoiding and burrowing behavior to make them drill out through the sieve holes and fall into the container or onto the bait tray for use as live bait.

(2) Cage rearing. Use iron strips to make several fly cages 60 cm long and 40 cm wide and 40 cm high, sealed around with nylon window screen. Open a round hole 20 cm in diameter on one side of the cage, and use a cloth sleeve open at both ends, with one end sewn to the edge of the hole, for adding culture material. Each cage can rear about 10,000 breeder flies.

(3) House rearing. House rearing or greenhouse rearing of fly larvae has high yield and quick results. The rearing house is generally a single-story house with an area of 15 to 20 sq m. The house is fitted with iron wire gauze and glass windows, and an exhaust fan is installed on the window. Inside the room there is a heating wall or stove to keep the temperature between 25 and 30°C, and the relative air humidity is adjusted to about 70%. An iron wire gauze is installed on the door and covered with a black cloth curtain to prevent flies from escaping. Multi-layer three-dimensional frames are placed indoors, and multiple plastic boxes 30 cm x 40 cm x 60 cm are placed on the frames, with feed put inside for the flies to eat and lay eggs. For breeder fly reproduction, put the saccharified feed directly into the plastic boxes, introduce breeder flies, and collect eggs to rear larvae. If fly larvae are produced in winter and autumn, indoor larvae rearing is generally used; in summer, outdoor larvae rearing is mostly used.

For indoor larvae rearing, first build heat-preservation, humidification, and ventilation facilities inside the house, and then build multiple cement tanks. Generally, the tanks are required to have an area of 2 to 4 sq m and a depth of 20 cm, with a lid made of window screen on top. The temperature should be adjusted to about 25°C. Then, add water to livestock and poultry manure at 80%, pile it up, cover it with plastic film, and compost and ferment it for more than 48 hours before use. When using it, adjust the feed pH to 6.5 to 7.0, put it into the tank at 40 to 50 kg per sq m, and spread it flat. Then evenly sprinkle the collected eggs on top. After 8 to 12 hours, larvae hatch out, and after 4 to 5 days, the reared larvae are collected for use.

Outdoor larvae rearing means that during the fly larvae growth season, after building cement tanks outdoors, the eggs are moved into the tanks to hatch into larvae. Generally, the feed in the tank is spread to a thickness of about 10 cm. During the rainy season, attention should be paid to sheltering from rain to avoid the tank overflowing and the larvae escaping. (4) Combined rearing in greenhouses and natural tanks. First build a cement pond 1.5 to 2.0 m long, 1.0 to 1.2 m wide, with 0.5 m intervals between them. On the outside, use bamboo poles or steel bars to support gauze netting to make a rearing pond. Determine the number of rearing ponds according to specific conditions. Then, build a plastic greenhouse on the outermost side. In this way, a rearing model combining a greenhouse and natural ponds is formed.