Male green bottle flies find partners by the flicker of sunlight on wings
A male green bottle fly identifies a young female by timing the glints of sunlight flashing through her beating wings. In a 2017 experiment, males chose a light diode blinking 178 times a second, a young female's wingbeat rate, over a real female held still. On cloudy days, the flies mate less.
Lucilia sericata is the best known of the green bottle flies, a metallic blue-green or golden blowfly slightly bigger than a house fly, found through temperate and tropical regions and fondest of warm, damp coasts. Telling it from its near twin, L. cuprina, takes a microscope, a count of bristles behind the head and a look at the colour of a leg joint.
Its life runs fast. A female lays clutches of 150 to 200 eggs, up to 3,000 over her life, choosing fresh carcasses and avoiding stale ones. Despite a popular belief, she rarely targets wounds, preferring damp fur or natural openings, and in sheep country eggs laid in wet wool cause the costly problem known as blowfly strike. Eggs hatch within nine hours to three days, faster in warmth. The larvae feed for three to ten days, then wander off, sometimes more than 100 feet, to bury themselves and pupate. A full generation can take just two to three weeks.
The larvae are strongly social, and their survival depends on it. Many maggots of the same age packed together develop faster and suffer less predation. Their constant churning raises the mass's temperature, and because each larva releases digestive enzymes, a crowd breaks down food far more efficiently than a loner could. Following chemical trails left by others, a group can collectively pick a feeding spot, even alongside other species, and split in two when overcrowding cancels the benefits.
Adults feed on nectar and pollen as well as carrion, making them useful pollinators. Some plants, such as the dead horse arum, exploit this by smelling like a corpse to lure egg-laden females. The larvae also have human uses, in maggot therapy and in forensic work, where their predictable growth helps time events.
Source: Common green bottle fly
