From Eggs to Butterflies
How Does a Population Grow?
How Many Survive? One female can lay several hundred eggs. Let's see how quickly the numbers could grow from one monarch generation to the next.
What is a Generation? A generation is one complete life cycle. A monarch can complete its life cycle in only one month. Let's count monarch generations and see how long it takes to reach a billion butterflies.
One Billion Butterflies If all of her eggs survived, one monarch butterfly could produce a billion butterflies in only 4 generations. She would have over a billion great-great-grandchildren!
What Limits Monarch Numbers? With such a high reproductive potential, why isn't the world swarming with billions and billions of monarchs? What factors might limit the population size?
Limiting Factors Monarch numbers can rise and fall for countless reasons. Here are some examples of limiting factors: Temperatures can be too hot or too cold; Precipitation can be too high or too low; Enemies can be many or few; Diseases can be deadly or mild. Food sources can be scarce or abundant...
Finding the Balance Scientists are still learning about the balance between the monarch's high reproductive potential and the factors that limit the population's growth. Probably less than 1% of all monarch eggs become butterflies, yet the population typically gets a little larger with each generation.
Report Your Sightings You can help scientists learn more about monarch populations by contributing your own observations.
What limiting factors keep the monarch population from growing exponentially?
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