Exponential growth of aphids
An aphid can reach reproductive age in 5 days.
A mature female can produce 3.5 nymphs per day by
parthenogenesis.
Assume no death, the population doubling time is about 2 days.
In 10 generations, the population will be 210 = 1024 individuals.
- The average individual is about 1-2 mm long; assume 1 mm for ease of calculation.
- 1mm * 1024 = 1024 mm, about 1 meter long if the aphids are lined up end-to-end.
In 20 gen, the population is 1,048,576, about 1,000 m, or 1 km.
In 30 gen, the population is 1,073,741,824, about 1,000 km. (Chicago to Washington, D.C. is 962 km)
In 40 gen, the population is 1,099,511,627,776, about 1 million km. (Earth to Moon is 385,000 km)
In 50 gen, the population is 1,125,899,906,842,624, 1 billion km. (Earth to Sun avg is 150 million km)
In 100 gen (200 days), the population is 1.2 * 1030, or 1.2 * 1024 km.
- Speed of light = 300,000 km/sec, or 1013 km/year. So the aphids are 1011 light years long.
- The Milky Way is 100,000 (105) light years across.
- The aphids are 106 (or 1 million) times the size of the Milky Way in 200 days, less than 1 year.
