Detailed Explanation of the Outdoor Ground-Level Maggot Farming Method
1. Selection of farming site. In a place far from housing and close to livestock and poultry sheds, choose a flat, tamped, level plot of ground raised above the ground surface to serve as the culture bed. Each culture bed has an area of about 4 square meters. Determine the number of culture beds according to the scale of rearing.
2. Making the frame. Use iron rods or wood to make a frame that can cover the culture bed, 50cm high, and paste a layer of kraft paper on the top and both sides of the frame to block direct sunlight. Then surround the frame with a layer of plastic film (the east and west sides can be lifted open) to make a cover, so as to help keep warmth and moisture. The frame is the same size as the culture bed, is movable, and can be moved away at any time, making it convenient to add feed and collect maggots.
3. Spreading manure. Use fresh chicken manure and pig manure, mix them evenly at a ratio of 1:1, then spread them out. Before spreading, first add water and mix until moist; the moisture level should be such that no water runs out. Then loosen the manure and spread it evenly on the culture bed at a thickness of 5~10cm, thinner when the weather is hot and thicker when the weather is cold. Finally, move the frame onto the culture bed to cover the manure layer, lift open the plastic sheeting on the east and west sides, and place a few dead rats or 0.5~1kg of animal carcasses, internal organs, fish intestines, etc. on the manure surface at the entrance to lure flies in to lay eggs.
Within 24 hours after spreading the manure, spray water several times according to the moisture requirements to keep the surface of the manure layer moist, so as to facilitate flies laying eggs and the hatching of fly eggs. If chicken manure is used, spraying water alone is enough; if pig manure is used alone, add 0.03% ammonia water or ammonium bicarbonate to the water to attract flies to come and lay eggs. After the flies have laid eggs on the manure layer for 1 day and night, lower the plastic sheeting on the east and west sides of the frame, press the surroundings tightly, and maintain the temperature inside the cover so that the fly eggs hatch in the manure layer.
4. Rearing maggots. Fly eggs can hatch into maggots after 8~12 hours at 25°C. After the maggots hatch, still spray water onto the manure layer according to the evaporation conditions, but do not allow water to accumulate in the manure layer, to prevent the maggots from suffocating. Use the opening and closing of the plastic sheeting on the east and west sides of the frame to regulate the temperature inside the cover; generally 20~25°C is suitable. In the later stage of maggot growth, the moisture of the manure layer should be reduced, and it is best to have moisture inside and dryness outside.
5. Collecting maggots for use. The maggots can be used 6~9 days after hatching. Because maggots are afraid of direct sunlight, when collecting maggots you can move the frame away and let sunlight shine on the manure layer; the maggots will then burrow to the bottom of the manure layer. Scrape off the surface manure, then pull apart the bottom-layer manure and maggots and let the chickens in to peck and eat them. This is the simplest method of collecting maggots. After the chickens have finished eating the maggots, gather the manure back into a pile, add 50% fresh manure and mix evenly, water it and spread it flat, and then begin rearing maggots again. By this method, based on 500g of maggots per square meter and each chicken requiring 20g per day, the maggots produced from 4 square meters of culture area in 1 cycle can provide 100 chickens with food for 1 day.