Hermetiaillucens (L.), the scientific name of the black water fly, originated in the savannah of South America, feeding mainly on the feces and carcasses of steppe animals, and then gradually spread throughout the American continent. By the middle of the last century, black waterflies were found from the southernmost tip of Argentina to Seattle in the United States. During World War II, the spread of war produced a large number of corpses, and the black water fly spread rapidly throughout the world with the US military, and is now distributed in most parts of the world's tropical, subtropical and temperate zones. The black water fly has been distributed in Guangdong, Guangxi, Hainan, Yunnan, Sichuan, Fujian, Hebei, Beijing and other regions in China. Adult black water fly is 15–20 mm long, black, with degenerated mouthparts and white translucent spots on the second ventral segment (Sheppard etal., 2002).
The life of the black water fly includes the ovary, larval, pupal, and adult stages. The larval stage is divided into 6 instar stages, of which the 6-instar larvae are called the pre-pupal stage, during which the larvae body becomes black, no longer molts, no longer eats, migrates out of the food to seek pupae, according to the different environments, the time of the pre-pupal stage of the black water flies varies greatly. The body of the pupae black water fly hardens and one end is cocked.
Eggs: Black waterflies are laid in the form of egg masses, the tip of which is tilted toward one end, giving the egg a scallop shape. The egg mass has obvious layering of 2 to 4, the arrangement between the eggs is relatively loose, and there are a large number of droplets adhering to the eggs. The single egg is milky white, translucent, oblong oval, like a grain of rice, 1.4±0.1 mm long, 0.3 mm in diameter, the first spawn is milky white, with translucent slurry, and the egg shell is extremely brittle and easy to break. As the inside of the egg develops further, the edges gradually become transparent and the middle part turns yellow, becoming a mid-stage egg. Continuing to develop into later stages, the yellow color gradually deepens indicating that the eggs are about to hatch. The hatching larvae are similar in size to the eggs.
Larvae: The larvae have a flattened body, no feet, and a pointed head. The young larvae are white, and the body color deepens later, gradually becoming dark brown and finally becoming brownish-black and entering the pre-pupal stage. The larvae are quieter, have a suspended death after being disturbed, and take about a minute to regain activity. The larvae are constantly migrating in the feed and are often concentrated in large quantities near feed suitable for feeding. The larvae have the property of protecting themselves from light, staying inside the culture feed during the day and moving to the surface at night. The first 3d larvae are small and difficult to observe. After 4d of age, the amount of feeding of the larvae increases significantly, and the individual grows rapidly. The body length of the larvae can reach about 20 mm.
Pre-pupa: Terminal larvae with a brownish-black body and very sparse short hairs at each body segment. The body length is about 20mm, the pre-pupal is no longer feeding, no longer molting, the body length is basically no longer changing, and the weight will continue to decrease. Pre-pupa crawls out of the feed, looking for hidden places to pupate, such as crevices or sand.
Pupae: Pupae are pupae and black throughout. After entering the pupal stage, the worm body cannot move. The pupal shell is hard and the body segments are dilated. The anterior half of the pupal is thickened and the tail is slightly bent.
Adults: Adults are 15-20 mm long. The antennae are broad, flattened, and long, with a black body and a bluish-purple luster, a white translucent spot on each side of the anterior side of the abdomen, and the tibial segments of the foot are white, and the rest is black.
Due to the outstanding performance in the treatment of kitchen waste and animal feces, in recent years, the black water fly as an important resource insect has been more and more developed and utilized, with the gradual deepening of related research, the black water fly will play a greater potential value!