|Mass Effect 3|
Even with all the Reapers' power, harvesting every sapient species in an entire galaxy can take decades or even centuries. The most time-consuming part of the process is gathering DNA from the population. To accelerate the effort, the Reapers follow a consistent procedure.
Victims who cooperate, surrender, or are captured by husks are sorted into camps. It is believed the husks possess receptors that allow them to analyze a victim's DNA through sight, smell, or touch. Victims that meet their standards are herded from the camps into processor ships. Those the husks insufficient are either turned into husks themselves or indoctrinated to serve as slave labor. The Reapers use this last option to give their victims false hope--many captives who would otherwise fight back become docile when they see members of their own kind obey and survive.
The processor ships reduce victims to a transportable liquid. Like in a slaughterhouse, the ships' design prevents victims from seeing or hearing what happens elsewhere so that they do not panic. The victims are ushered into locking pods, then rent apart and dissolved into paste that is flushed to storage vats.
The rate of killing is phenomenal. Intelligence estimates suggest there are more than 400 processor ships on Earth, killing approximately 1.86 million humans per day. In combination with battlefield deaths, disease, and famine, this pace will result in the complete depopulation of Earth within a decade. As the husks and indoctrinated slaves build more slaughtering facilities, the kill rate can only increase.