Caged Fly Daily Rearing and Management Technical Manual

I. Understanding the morphological characteristics and living habits of the housefly

(1) Morphological characteristics: The housefly is a holometabolous insect, and its life cycle goes through 4 stages: egg, larva, pupa and adult.

(2) Living habits

① Life history: Under natural conditions, the number of generations of the housefly each year varies by region. Under artificially controlled temperature conditions, as long as the temperature is suitable, the housefly can reproduce throughout the year.

② Duration of each developmental stage: The generation period of the housefly is shorter than that of other insects, and its development speed is extremely fast. The developmental duration of each stage is closely related to temperature; within the suitable temperature range, as temperature rises, the developmental duration shortens. At 25-35 degrees C, the generation period is only 10-15 days, of which the egg stage is less than 1 day, the larval stage is 4-6 days, the pupal stage is 5-7 days, and the adult lifespan is 1-2 months.

③ Activity habits: Adults like to be active outdoors during the day, and at night mostly rest on trees or indoor ceilings; when the temperature is low, they like to gather in warm places.

④ Reproductive habits: Adults reach sexual maturity 2-5 days after emergence and begin mating and laying eggs. In actual production, each batch of breeding flies should be culled in a timely manner after 20-25 days of rearing.

⑤ Feeding habits: Adult houseflies like to feed on liquid foods with high protein content, and water is a necessary condition for adult survival. Brown sugar and milk powder are the best foods for adults; adults fed with milk powder or milk powder + white sugar/brown sugar can live for more than 50 days. Adding substances such as vegetables and fruits to the feed to supplement vitamins and trace elements helps increase egg production. Feeding adults with fresh maggot slurry increases egg production by 10%-20% compared with using milk powder.

Larvae like to feed on decaying organic matter, and various degrees of decaying organic matter can serve as their nutrient source. Artificial feed that has been fermented for about 6 hours is more suitable for feeding to larvae.

⑥ Pupation habits

⑦ Relationship with temperature and humidity: Temperature directly affects the survival, growth and development, and life activities of the housefly. In actual production, controlling the larval rearing temperature at 25-35 degrees C is relatively suitable; below 22 degrees C the growth cycle is prolonged, and above 40 degrees C the larvae will crawl out of the culture medium to seek a cool place with a suitable temperature. Adults stop developing below 12 degrees C and do not mate or lay eggs; below 15 degrees C they cannot lay eggs. At the suitable temperature of 20-30 degrees C, their lifespan is the longest, reaching 50-60 days. At 30 degrees C adults are most active, and above 30 degrees C they rest quietly in cool places; if the temperature exceeds 35 degrees C, breeding flies become restless and uneasy, at 39 degrees C they cannot lay eggs, at 40 degrees C breeding flies gradually die, and above 45 degrees C is the lethal temperature.

The growth and development of housefly eggs, larvae and pupae require the culture substrate to be moist but not flooded, with a water content of 50%-60% being most suitable. Research shows that substrate water content has a great influence on the development of housefly eggs; when the water content is 60%, the egg stage is the shortest at 18 hours and the hatching rate is the highest; the optimal substrate water content for larval survival is 60%-70%; pupal development has lower humidity requirements, and 40%-50% humidity is relatively suitable. Adults can hardly survive away from water; during the adult stage, an air relative humidity of 50%-80% is appropriate. Adults begin drinking water and feeding 1 hour after emergence. Generally, after 2-3 days without food and water, all die, and in production this is often used to cull adults after egg laying.

II. Key technical points for caged fly rearing

(1) Determination of rearing scale

The size of the rearing scale is determined according to the expected daily output. Taking a rearing farm with a daily output of 100 kg of fresh fly maggots as an example, the following aspects should be considered when designing the farm:

① Adult rearing scale: For every 10,000 adult houseflies, the eggs laid daily during the peak egg-laying period, after 5-6 days of rearing, can produce 4 kg of fresh maggots. If the daily output of fresh maggots is 100 kg, then 250,000 adults at the peak egg-laying period need to be reared. Considering the influence of other factors, the breeding fly rearing scale of one production unit should reach at least 300,000 adults. If the culling and replacement of breeding flies is also considered, one replacement cycle requires 4 days. Therefore, two units of breeding fly production scale must be prepared in order to ensure a continuous supply of egg masses needed for a daily output of 100 kg of fly maggots.

② Area required for rearing adults  At present, there are 2 methods for rearing adults: cage rearing and room rearing. A room of 15-20 cubic meters can hold 20-25 fly cages of 0.5 cubic meters placed in three dimensions, and the adults reared can satisfy the egg masses needed for a daily output of 100 kg of fly maggots.