Monarch butterflies are famous for their striking appearance and fascinating transformation from a white, yellow, and black caterpillar to a beautiful orange and black flying butterfly. The percentage of these caterpillars successfully turning into adults depends on various factors.
What percentage of monarch caterpillars become butterflies? The survival percentage of monarch caterpillars that turn into butterflies is 2-8% in the wild and 85-95% in captivity because of a secure and controlled environment. Various factors determine the survival rate of these caterpillars, such as predation, temperature fluctuations, cleanliness, parasites and diseases, living conditions, food availability, and habitat loss.
They lay eggs on the host plant because monarch caterpillars feed on the specific milkweed plant and do not eat the leaves of other plants in the surroundings.
Butterflies die after laying eggs because they naturally have short lifespans but contribute to an increase in the overall population if these eggs hatch successfully and complete all growth stages.
What percentage of monarch caterpillars turn into butterflies?
The percentage of monarch caterpillars turning into adults varies with their environment and the situations around their habitat.
For example, according to an estimation, 2-8% of eggs hatch, and caterpillars complete the metamorphosis process to become adult butterflies in the wild.
Moreover, my friend told me that one or two eggs out of a hundred survive and reach adulthood in the wild.
He said monarch butterflies lay 300-400 eggs, and only 6-8 eggs will successfully undergo the metamorphosis and become adults if they grow in their natural habitats.
However, the percentage increases to a great extent in captivity or controlled environments, such as 85-95% of eggs successfully hatch and caterpillars complete the metamorphosis to become adults.
The controlled environment allows better growth and a secure environment, which causes an increase in their survival percentage.
For example, my childhood friends collected 100 eggs from the milkweed plant, and all of them hatch into caterpillars and become beautiful flying insects after a few months.
What factors determine the survival rate of monarch caterpillars?
Various factors affect the survival rate of monarch caterpillars because they are sensitive and prone to many accidents and death.
Predation
Predation is one of the most significant factors that affect caterpillars because they cannot fly and crawl on the ground or plants.
Various predators in the wild seek monarch caterpillars and eat them, which do not allow them to complete the growth cycle in the wild. They die in the larval stage and do not enter adulthood.
However, they are less prone to attacks in captivity and controlled habitats; therefore, the survival percentage is high compared to open environments.
Wasps, hornets, spiders, ants, and other insects eat clusters of monarch eggs if they find them during foraging and cause an increase in mortality rate by reducing the hatching rates.
Temperature fluctuations
They need an appropriate temperature to grow and complete the development process, as the harsh weather causes them to die and not reach adulthood.
For example, my friend told me that hot weather and direct sunlight cause them to die and the survival rate reduces, as he noticed many dead monarch caterpillars on the ground in June when the temperature rises more than 40 degrees Celsius.
They did not find shady areas around these milkweed plants in an open environment. Similarly, the freezing temperature also causes them to die in their larval stage.
Cleanliness
The cleanliness around their habitat also influences their survival percentage in the wild and captivity. For example, the frass accumulation in the cage causes mold and parasites, which leads to several health problems, and they cannot pupate properly.
Moreover, my aunt worked in an entomology department, and she told me that cleanliness in captivity is one of the prime reasons for successful metamorphosis because the pathogens, bacteria, and mold affect their growth.
In addition, she told me that the chemical contaminants, air pollution, and poor habitat quality can affect their well being.
She further advised me to clean the cage of my captive monarch butterflies once or twice a day, depending on the number of caterpillars living there. You should maintain proper ventilation and airflow for them to grow.
Parasites and diseases
They are prone to parasitic infection and other bacterial diseases, which affects the survival of monarch caterpillars and the number of these crawling insects transforming into adult butterflies.
According to research, the parasites eat the tissues and internal organs and cause death. Moreover, the adult butterfly can spread these parasitic infections.
In addition, my neighbor also studied monarch butterflies and the diseases that affect their population.
He said the OE parasite causes the caterpillars to have deformities if they survive to emerge from the chrysalis and enter adulthood or kill them, reducing their numbers that become adult insects. However, they cannot live longer and die soon after coming from the chrysalis.
Living conditions
The monarch caterpillars living in captivity are more likely to turn into butterflies because of the safe environment and less predation.
However, I read in a research paper that they are weaker than the butterflies thriving in the wild. The researchers find that the captive caterpillars turning into adults die soon during migration, and the wild ones survive and migrate successfully to their wintering sites.
Moreover, the living conditions, like heavy rainfall and windstorms affect the percentage that turns into adults.
Availability of food
Food is their essential need, and they cannot thrive without it. They need to consume a lot of milkweed leaves to survive and grow.
The percentage decreases if they do not find enough milkweed around their habitats, and food deficiency can lead to death.
The large number of caterpillars on one host plant causes overcrowding, and they do not get enough food to eat, leading to low survival rates.
They get more food in captivity because the owners feed them many times a day, while they do not have access to more food in the wild. It also causes a decreased percentage of their survival in the wild compared to captivity.
Habitat loss
The habitat loss due to urbanization causes them to die, and a reduction in the number of monarch caterpillars transforms into adult flying insects.
In addition, the pesticide and herbicide use on their host plants also leads to poor habitat quality and chemicals getting inside their bodies, which causes reduced growth or death.
Therefore, it is better to wash the leaves if you cut them from outside the house to minimize the chances of pesticide chemicals and parasites.
What do people say about it?
The captive monarch caterpillars have a higher percentage of successful transformation into butterflies than the species in the forest and wild.
“I have five caterpillars in captivity, and four metamorphose into adults within a couple of months.”
Habitat destruction causes them to die and increases the mortality rate because they do not find enough food and camouflaging spots in their surroundings.
“I grew many milkweed plants in my garden every spring to ensure the survival and increase the number of young monarch caterpillars to turn into adults, as I saw many of them turning into butterflies every year by feeding on these plants.”
Mold and excessive moisture in their habitat cause parasites and bacterial diseases, which reduce the survival percentage.
“I found six caterpillars dead last year due to the parasites and pathogens accumulated inside the enclosure due to mold and tried my best to keep the cage clean after this to ensure the survival of remaining caterpillars.”
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