Formulae for the standard deviation. Whilst it is not necessary to learn the formula for calculating the standard deviation, there may be times when you wish to include it in a report or dissertation. The standard deviation of an entire population is known as Ï (sigma) and is calculated using:
After 8-20 hours, the egg hatches and the fly enters the maggot stage. It begins to feed on whatever the egg was laid on, usually decomposing flesh. The maggot gorges itself with food until it is ready to enter the pupal stage, at which point the maggot travels away from the food source to a moist spot.
A female blowfly lays up to 300 eggs at one time, and with numerous females visiting a corpse, the number of maggots can be immense. For example, 48,562 maggots were found on a 156 g piece of meat after 24 hours exposure. However, because this was insufficient food to sustain them, only 231 flies finally emerged. In warm weather, conducive to fly growth, maggots can consume 60 per cent of a human body in less than a week.