Calliphoridae

The Calliphoridae, a family within the order Diptera, are commonly called blowflies, carrion flies, bluebottles, or greenbottles. There are nearly 1,900 known species. Their larvae, known as gentles, are frequently used as fishing bait. The family is considered polyphyletic, and how its subgroups should be classified is still debated; some groups, like Bengaliidae and Helicoboscidae, are sometimes treated as separate families.

Adults are usually shiny with metallic coloring, often in blue, green, or black on the thorax and abdomen. They have three-segmented antennae with a bristle-like arista that is plumose along its entire length, and the second antennal segment has a distinct groove. Their wings have branched Rs 2 veins, a frontal suture is present, and the calypters are well developed. Bristle patterns help distinguish species; all blowflies have bristles on the meron, and identification looks for two notopleural bristles and a hindmost posthumeral bristle located lateral to the presutural bristle. The thorax has a continuous dorsal suture across the middle and well-defined posterior calli, while the postscutellum is absent or weak. The costa is unbroken, and the subcosta is visible.

Most studied blowfly species are anautogenous—females need a substantial protein meal (about 800 μg per ovary pair in *Phormia regina*) to develop mature eggs. It is thought females visit carrion for both protein and egg-laying, though this is not proven. Eggs are yellowish or white, about 1.5 mm by 0.4 mm, and look like rice grains. A female typically lays 150–200 eggs per batch and is iteroparous, laying around 2,000 eggs in her lifetime. The sex ratio is usually 50:50, except in two *Chrysomya* species (*C. rufifacies* and *C. albiceps*), where females are either arrhenogenic (producing only males) or thelygenic (producing only females). Hatching takes 8 hours to a day. Larvae go through three instars, separated by molts, which can be told apart by the posterior spiracles. Larvae use proteolytic enzymes in their excreta and mechanical grinding with mouth hooks to break down proteins on carrion or livestock. Blowflies are poikilothermic; growth rate depends heavily on temperature and species. At about 20 °C, *Phormia regina* takes 150–266 hours (6–11 days) to go from egg to pupa. After the third instar, the larva leaves the corpse, burrows into the ground to pupate, and emerges as an adult 7–14 days later.

Adult blowflies are occasional pollinators, attracted to flowers with strong rotting-meat odors, like the American pawpaw or dead horse arum. They likely use nectar as a carbohydrate source for flight, but how and when is unknown. One study found that visual stimuli from their compound eyes cause them to extend their legs from flight position to land. Most larvae are scavengers of carrion and dung, making up the majority of maggots in such material, though they are often found alongside larvae from Sarcophagidae, Muscidae, and other acalyptrate muscoid flies.

Predators include spiders, beetles, frogs, and birds such as chickens. In Mexico’s Chihuahuan desert, the fungus *Furia vomitoriae* infects bluebottle flies, forming masses of conidiophores that erupt through the intersegmental areas on the abdomen’s dorsum and eventually kill them.

Blowflies feed and develop in microbially dense, chemically dynamic substrates like carrion and necrotic wounds. Because they, their larvae, and the necrobiome’s microbiota share resources, blowflies act as both pathogen vectors and facultative bacterivores. Bacterial digestion by *Lucilia sericata* larvae is well-established for some microbes like *Escherichia coli*, but other microbial taxa may be spared or excluded. While *Providencia* bacteria harm *Cochliomyia macellaria* larvae under gnotobiotic conditions, and several blowfly species benefit from mixed microbial environments, the specific taxa and causal mechanisms—which would clarify whether microbes persist passively, parasitically, or mutualistically—remain unknown. One study found *Lactobacillus*, *Proteus*, *Diaphorobacter*, and *Morganella* (in decreasing order) associated with third-instar *Lucilia sericata* salivary glands, suggesting a balance between lactic acid-producing Gram-positive and urease-producing Gram-negative taxa. However, studies on altered substrate pH have not yet linked their findings to blowfly pH preferences, fermentation, or microbial activity.