Detailed Explanation of the Artificial Cage-Rearing Method for Sterile Fly Larvae

    To raise flies, you only need 12m of 22-mesh nylon gauze to make one net cage, and with a dozen or so trays you can produce on a large scale. A 2 sq m net cage can hold 60,000 breeding flies, fed 100g of milk powder per day, and can produce 12kg of fly larvae daily using only 24kg of wheat bran or 48kg of poultry and livestock manure. The eggs produced each day are placed in wheat bran or poultry and livestock manure to rear, and by the fourth day the larvae can be harvested to feed Thailand tiger frogs, stonefrogs, forest frogs, walking catfish, giant salamanders, soft-shelled turtles, scorpions, poultry and livestock, etc. Larvae can be produced every day and are available for use daily. They are extremely easy to raise, and after one introduction of breeding stock no further introduction is needed. The total investment is only 300-500 yuan to get started, and the scale can be large or small depending on what is needed.

I. Living Habits of the Housefly

At a room temperature of 20°C-30°C and a relative humidity of 60%-80%, the housefly pupa completes its development in five days, going from soft to hard, and from cream yellow, light brown, and dark brown to black, until finally the adult fly breaks out of the shell at the front end of the pupa. The newly emerged adult fly can only crawl, not fly. After one hour, it spreads its wings and begins to feed and drink. Adult flies are lively and active during the day and rest motionless at night. After three days they reach sexual maturity, and males and females begin to mate and lay eggs. Days 1-15 of age are the peak egg-laying period, and by day 25 of age they basically lose the ability to lay eggs. Fly eggs hatch into larvae in half a day to one day, and the larvae develop in poultry and livestock manure, usually becoming pupae on the fifth day. One generation of the fly is about 28 days. Temperature and the nutritional content of the larval feed have a great influence on the growth and development of the larvae. Generally, within a room temperature range of 20°C-30°C, the higher the temperature and the thicker the nutrient layer, the faster the larvae grow and develop, and the larger the pupae they become.

II. Rearing of Breeding Flies

Breeding flies should be kept in a fly room. The size of the breeding fly room is made according to what is needed, and an old room can also be converted for it. Rearing racks are set up inside the room, made of iron or wood. On each shelf layer are placed fly cages made of nylon gauze. The cages are 200cm long, 80cm wide, and 80cm high. The breeding flies are kept inside the cages, with 60,000 breeding flies per cage. A 35cm-long zipper is installed at the lower middle part of the fly cage to facilitate adding feed, adding water, and collecting eggs. 60,000 adult flies are fed 100g of milk powder per day. The milk powder is placed on the surface of moist wheat bran for the breeding flies to feed on and to lay eggs in. A gauze cloth is placed in the sugar-water basin to prevent the breeding flies from drowning. The feed and water are changed once a day. Every morning, eggs are collected once from the breeding fly cage and sent to the larvae room for rearing. Breeding flies lay the most eggs between 8 a.m. and 3 p.m. each day. Each batch of breeding flies is culled after 15 days of egg laying; the breeding flies are placed together with the cage into water to drown them for use as poultry or aquatic feed, and then a new batch is swapped in.

III. Rearing of Fly Larvae

For rearing fly larvae, you can use a larvae-rearing pool built of bricks with a side height of 12cm and an area of 1-5 sq m, or use plastic trays on a bamboo or wooden rack to rear larvae. A plastic tray with a diameter of 50cm can rear 1.5kg of larvae using only 3kg of wheat bran, and after 3-4 days of rearing they can be collected for use. The sources of larval feed are fairly broad, and the costs of different larval feeds vary, so a reasonable choice can be made. Wheat bran has a relatively high nutritional content and is also somewhat more expensive, and is generally used to breed fly stock, while low-cost distillers' grains, soybean residue, and the like can be used as feed for commercial larvae. If wheat bran is used as larval feed, generally 1kg of wheat bran can produce 0.5kg of fly larvae. When using it, water must be added and mixed evenly; the suitable degree of dryness and wetness is that water comes out when squeezed by hand and it breaks apart when touched (water content 60%-65%). If semi-dry and wet materials such as distillers' grains or soybean residue are used, no water needs to be added when using them for rearing. The specific method for rearing larvae: take the egg-laying tray out of the net cage, pour the fly eggs and wheat bran feed into the tray, add larval feed such as distillers' grains, soybean residue, or wheat bran, and mix slightly. Note: do not leave the fly eggs exposed on the surface of the larval feed, to avoid loss of water and loss of vitality. The thickness of the larval feed is based on the standard that the fermentation temperature within the larval feed is not higher than 40°C and not lower than 20°C, generally 5-10cm. In summer when the temperature is on the high side, the larval feed should be appropriately thinner; conversely, in winter when it is on the low side, the larval feed can be appropriately thicker. If poultry and livestock manure is used, it is best to use EM bacteria to ferment and deodorize it before use. As for the ratio of feed to larvae, taking pig manure as an example, generally 4-5kg produces 1kg of fresh larvae. No matter which material is used to rear larvae, the dryness and wetness of the larval feed should be kept at 60%-65% as suitable.

IV. Collection of Fly Larvae

Taking advantage of the fly larvae's aversion to light, collection is carried out. Use a manure rake on the surface layer of the feed in the larvae-rearing pool, raking continuously, and the fly larvae will burrow downward. Remove the surface layer of manure feed. Repeat this method many times, and in the end a small amount of manure feed and a large number of fly larvae remain. The separated fly larvae, after being washed clean, can be used directly to feed poultry and livestock, or can be baked at 200-250°C for 15-20 minutes, then dried and stored for later use. Note: if factory-style fly larvae and earthworm rearing technology is adopted, the insect manure is automatically separated without manual work.