Ecological habits of flies
Biologically, flies are typical of "completely metamorphosed insects." Its life goes through four periods: eggs, maggots (maggots), pupae, and adult insects, and the forms of each period are completely different. The breakdowns are as follows:
1. Eggs are milky white, banana-shaped or oval, about 1 mm long. There are two crests on the back of the egg shell, the membrane between the crests is the thinnest, from which the larvae emerge when they hatch. The development time of the egg stage is 8 to 24 hours, which is related to the ambient temperature and humidity, and the egg does not develop below 13 ° C, and dies below 8 ° C or above 42 ° C. The incubation time of eggs decreases with increasing temperature in the following ranges: 20 hours at 22 °C, 16 to 18 hours at 25 °C, 14 hours at 28 °C, and 8 to 10 hours at 35 °C. The humidity of the growth matrix also has an impact on egg hatchability: the hatching rate is highest when the relative humidity is 75% to 80%, and the hatching rate is significantly reduced when it is below 65% or above 85%.
2, larvae The larvae of flies, commonly known as fly maggots, have three ages: 1 instar larvae are 1 to 3 mm long and only have a posterior valve. After molting, it becomes 2 years old, 3 to 5 mm long, has anterior valve, and has 2 clefts in the rear valve. The molt again is 3 years old, 5 to 13 mm long, and the posterior valve is 3 cracked. The body color of fly maggots changes from transparent and milky white to milky yellow at 1 to 3 years until mature and pupate. The 3rd instar larvae are oblong-conical, with a fine tip at the front and a truncated posterior end, with no eyes and no feet.
The characteristics of the life of the fly maggot are that they like to drill holes, are afraid of strong lights, and live in the dark places of the breeding creatures all day long. It has a variety of food, all kinds of rotten fermented organic matter, are its delicacies. The larval stage is a critical period in the life of the fly, and its growth and development are directly related to the individual size and reproductive efficiency of the fly. The main factors affecting the growth and development of maggots are as follows:
(1) Temperature: Its level is directly related to the development time of fly maggots. The optimal ambient temperature (medium temperature) is 34 to 40 °C, and the development period can be shortened to 3 to 3.5 days; when the temperature is 25 to 30 °C, the development period is 4 to 6 days; when the temperature is 20 to 25 °C, the development period is 5 to 9 days; when the temperature is 16 °C, the development period is as long as 17 to 19 days. The minimum temperature during development is 8 to 12 °C, and above 48 °C, death occurs.
(2) Humidity: The suitable environmental humidity of maggots in 1-2 years is 61%~80%, and the optimal humidity is 71%~80%. The suitable environmental humidity of maggots in the 3rd age is 61% to 70%, and more than 80% cannot develop normally. It can be seen that the development of maggots requires a certain humidity, but the higher the better. In production practice, the suitable humidity is 65% to 70%; below 40%, the maggots are stagnant in development, the pupals are very rare, and even lead to the death of the maggots.
(3) Food: One of the important ecosystems of fly maggots is omnivorous, and it feeds on the spot in its habitat. Someone once found as many as 76,400 fly maggots and pupae in 1.5 square meters of pig manure! Animal feed, plant feed and even protein in microorganisms are all nutrients that maggots like to ingest. The quantity, quality, fermentation temperature and moisture content of food are directly related to the developmental effect of maggots. In the 3rd instar, maggots stop feeding after maturity, and under the conditions of low temperature of 15 to 20 °C and low humidity, they often leave the breeding site and drill into the nearby soil loose place to pupate. Thousands of pupae of houseflies have been found in a crack in the cracks in the cement floor at the base of a winery's courtyard.
(4) Ventilation: Air circulation is conducive to the growth and development of maggots. In garbage dumps, maggots are often distributed in the corners and roots of walls with large gaps. Mastering the growth characteristics of the above-mentioned fly maggots and using them to guide the actual production is of great benefit to improving the efficiency of maggot farming.
3. Pupa pupa is the third metamorphosis in the history of fly life. It is barrel-shaped, i.e. pupae. Its body color changes from light to dark, and finally becomes chestnut brown, which is 5 to 8 mm long. Metamorphosis is constantly carried out within the pupal shell, and once the prototype of the fly is formed, it enters the feathering stage. When feathered, the frontal sac of the fly's head alternately expands and contracts, squeezing the tip of the pupal shell apart and crawling out, passing through loose sand or other cultures to reach the surface. From pupal to feathering, it is called pupal stage. The external factors that affect the growth and development of pupae mainly include:
(1) Temperature: After the 3-instar fly matures, it tends to pupate in a slightly lower temperature environment. However, below 12 °C, the pupa stops developing; above 45 °C, the pupa dies. Within the suitable range, as the temperature increases, the pupal stage decreases accordingly. At 16 °C, it takes 17 to 19 days; at 20 °C, it takes 10 to 11 days; at 25 °C, it takes 6 to 7 days; at 30 °C, it takes 4 to 5 days; at 35 °C, it takes only 3 to 4 days, which is the optimal development temperature. Pupae are characterized by being relatively hardy. According to the test, the housefly pupae returned to normal room temperature after 4 days of refrigeration at a temperature of 1 °C and an ambient humidity of 85%, and the feathering period was only 1 day later than the normal pupal stage; refrigeration in the above environment for 3 days did not reduce its feathering rate.
(2) Humidity: According to the test, the best culture material suitable for pupae development has a humidity of 45% to 55%, higher than 70% or less than 15%, which will significantly affect the normal feathering of pupae. If the pupa is soaked in water, the longer the time, the lower the pupal pupal rate of fly maggots, and the lower the pupal feathering rate. Someone once caught 1,000 flies from liquid garbage, and after being transferred to a dry environment, 1 of them failed to feather into adult flies. It is worth mentioning that if the nutrients of the cultured fly maggots are insufficient, the fly maggots are barely pupated without full development, and the pupae can also hatch into adult flies, but more than 95% of the adult flies are males, only eat food and do not lay eggs, and all die in a week or so. Therefore, the fly maggots used to keep pupae must be fattened with sufficient nutrients, and the greater their female proportion. Only when there are more female species flies, the amount of eggs laid can be guaranteed, and the yield will be stable.
4. Adult flies (flies) Adult flies that are feathered from pupae need to go through several stages of "stationary - crawling - stretching - spreading wings - hardening of the body wall" in order to develop into adult flies with the ability to fly, feed and reproduce. The housefly, which has just feathered out of the pupa, has a soft, pale gray body wall, wings that have not yet been spread, and the frontal sac that has not retracted. Later, the wings are extended, the epidermis hardens and the color deepens, and after 1 to 1.5 hours, the wings can fly. Under the conditions of 27 °C, adult flies do not begin to move and feed until 2 to 24 hours after feathering. Its ecological habits are as follows.
(1) Feeding habits and lifespan The feeding habits of flies depend on their species. There are those who specialize in sucking nectar and plant juices, and those who specialize in cannibalizing human, animal blood or animal wound blood and eye and nasal secretions. The common house flies, large-headed goldflies, mercerized green flies, lilies, and hemp flies belong to omnivorous flies, that is, widely eating human food, livestock and poultry secretions and excrement, kitchen scraps and organic matter in garbage. They have a strong tendency for sugar, vinegar, ammonia and fishy taste. According to research, if the female flies are simply supplied with water, sugar and carbohydrates, although they can grow, the ovaries cannot develop and lay eggs; only by feeding protein feeds or a variety of amino acids can they lay eggs normally. If royal jelly is used to feed female houseflies, it can shorten the pre-spawning period and increase the amount of eggs. Factors that affect the lifespan of flies are temperature, humidity, food and water. The temperature is 25 °C ~ 33 °C, and the air humidity is 60% ~ 70. Female flies live longer than males, with a lifespan of 30 to 60 days, and up to 112 days under laboratory conditions. In low-temperature overwintering conditions, flies can live for up to half a year. The breeding adaptability of flies is very strong. The breeding organisms of the fly species can be roughly divided into human feces, livestock manure, decaying animals, rotten plants, garbage, and sewage. Fly maggots are very adaptable, almost all of the above six types can breed, especially in livestock dung, fermented plants, and secondly like to breed in human dung, rotten animals.
(2) Activity and habitat Flies are insects that are frequently active during the day and have obvious phototropism. At night, it perchs still. Activities and habitats depend on fly species, season, temperature and region. In some seasons, stable rot flies, summer side flies, and city flies also invade the house. The big-headed golden fly, the mercerized green fly, the fly, the volley fly, the hemp fly, etc. are mainly active and inhabit the outdoors. The activity of flies is greatly affected by temperature. It can only crawl at 4 ~ 7 °C, can fly at 10 ~ 15 °C, can feed, mate and lay eggs above 20 °C, is particularly active at 30 ~ 35 °C, stops being active due to overheating at 35 ~ 40 °C, and dies at 45 ~ 47 °C. Flies are good at flying. The flight speed can reach 6 to 8 kilometers per hour, and the maximum flight speed is 8 to 18 kilometers per day and night. However, it is usually active within a radius of 100 to 200 meters in the breeding ground, and most of them do not exceed 1 to 2 kilometers. The way flies overwinter is quite complex. It can overwinter in a pupae state, as well as in the form of fly maggots and adults. In the northern cold and temperate regions, there are no active houseflies in nature, but there are still adult flies in the artificially heated indoors, and the greenhouse greenhouse often becomes the birthplace of a large number of flies in the warm spring of the following year. In Jiangnan and parts of Northern China, where the average winter temperature is below 0 °C, flies can subtly overwinter in a pupal state, and maggots covered with livestock and poultry manure can be found in a few areas of the dormant female flies. In tropical South Asia, where the average temperature is above 5 °C, flies do not have a dormant state and can continue to breed.
(3) Male and female separateLy from their individuals: the smaller individuals in the group are generally males, and the larger individuals are generally males and females; 2. Look at their stomachs, male and male: the stomachs of male flies are small and flat, and the stomachs of female flies are large and round; 3. Look at their butts into females: the ass of male flies is round, and the butts of female flies are pointed.
(4) Mating and reproduction At the right temperature, male houseflies can sexually mature and mate 18 to 24 hours after feathering and female houseflies 30 hours after feathering. Mating time is generally between 5:00 and 7:00 in the morning. Sensitive sense of smell, extrasexual hormones, and vision are all important factors in promoting mating between male and female flies. A pair of mating houseflies can stay together for a long time, crawl together, fly in pairs, and the effective mating time is up to 1 hour. The vast majority of houseflies mate only once in a lifetime. The semen of the male fly can be stored in the fertilized sac of the female fly for a long time, stimulating egg laying, and for 2 to 3 weeks the fly egg is continuously fertilized without having to mate with another male fly. This is rare in other insects. This is an important reason why flies are highly fertile. The peak period for spawning is from 17:00 to 19:00 every day. The length of the pre-spawning period (i.e., the time from feathering to the first spawning) of female flies is closely related to ambient temperature: an average of 9 days at 15 °C, only 1.8 days at 35 °C, and no spawning at below 15 °C. After mating, female flies often crawl into the breeding crevices such as human and animal feces, and extend their spawning tubes to lay eggs deep in the breeding organism, so that the eggs are fully protected. Flies have amazing fecundity. It has been observed that the houseflies in the laboratory lay about 100 eggs per batch, and a female fly can eventually lay 10-20 batches of eggs, with a total spawning capacity of 600-1000 eggs. In nature, each female fly can also lay 4 to 6 batches of eggs in her lifetime, with an interval of 3 to 4 days in each batch, and each batch lays about 100 eggs, and the final number of eggs is 400 to 600 eggs. Even in North China, houseflies can reproduce 10 to 12 generations a year, according to the most conservative estimates, each female fly can produce 200 offspring, then 100 female flies only need to go through 10 generations, the total number of flies bred will reach 2 trillion billion!
(5) Natural enemies Although flies are fertile and the family is prosperous, 50% to 60% of future generations die due to predators and other disasters. There are three types of natural enemies of flies: one is predatory predators, including frogs, dragonflies, spiders, praying mantises, ants, lizards, geckos, insectivorous flies and birds. Chicken manure is a breeding organism of houseflies and stable flies, but there are often ferocious giant claws and cockroaches that prey on the eggs and maggots in the feces. The second is parasitic natural enemies, such as bees, small bees and other parasitic bees, they often lay eggs in maggots or pupae, hatching larvae and then eat maggots and pupae. It has been found that 60.4% of the pupae dug up in the spring were infested by parasitic wasps and died. The third is the natural enemy of microorganisms. Japanese scholars have found that Morita bacillus can inhibit the breeding of flies, and Chinese scholars have also found that the spores of "fly monomycete fungus" will infect flies with monococcus fungus if they fall on flies. All of this deserves the attention of maggot farmers.