In many nations, no butterfly is as recognizable as the monarch. Monarchs were first studied a few hundred years ago, and there’s been a proliferation of new information since, given that butterfly study is quite a clear-cut field of research. Add to that the characteristic orange and black appearance of the monarch, and the patterns are even easier to follow. The question of how long do monarch butterflies live has been an interesting one, as the answer sets them apart from many other species of butterfly.
How Long Do Monarch Butterflies Live
The most essential ingredient to how a monarch butterfly lives is milkweed. Milkweed is the only plant that the monarch caterpillar can eat during the growing phase of life. That means that when an adult female monarch is laying eggs, she must have access to milkweed. If she lays her eggs elsewhere, with no milkweed around, her babies will starve upon hatching. Butterflies can drink nectar from any old flower, but to make it to adulthood, or even the chrysalid phase, they must eat from the proper host plant. These plants are typically native to the area, and while there is a range of acceptability for many other species, only milkweed will do for the monarch. The milkweed that the larva eats makes the monarch inedible, or at least unpalatable, to many predators. It is possible that the colors, dots, and stripes of the monarch and its caterpillar are intended as a warning to those birds who would normally see them as food.
The lifespan of many monarchs has the potential to be much longer than other butterflies because some of them are migratory. In fact, specific species of butterfly are the only insects that will travel thousands of miles each year in order to survive. But how long they live all depends on when exactly they are born. A monarch who hatches from the chrysalis in spring or early summer will live for approximately two months at best. Those monarchs born in late summer will get the opportunity to migrate to Mexico for the winter, live out those months in warmer climes, and return north when the cold weather breaks.
The reasons that the monarch butterflies make this journey are completely understandable. Proper food and warm temperatures are mandatory for the monarch to live. Unlike many other insects, monarchs cannot survive a winter in a four-season area. Add to that the fact that milkweed and other flowers for feeding don’t survive harsh cold, and monarchs have all the motivation they need to move on down south.
So why don’t all monarchs live as long as the migratory generations? Temperature and daylight make the migratory monarch much different from the spring and summer adults in previous generations. The shorter, cooler days have a profound effect on the hormones and nervous systems of monarch butterflies born in late summer and early fall. The milkweed they ate to grow is drier, and so the nutrient levels are different, affecting physiology. They do not always emerge in adulthood nearly ready to mate, as the generations born before them that season did. Therefore, to continue their lineage, they have to seek out better food and warmer temps. The mystery is how millions of monarchs know where to go- the ones before them definitely hadn’t left a map. It has to be chalked up to the position of the sun, and good old animal instinct. While making the trip to Mexico, the North American monarch may find milkweed to lay eggs on in southern states, if they have reached reproductive maturity. Those monarchs, unlike their parents, will probably not enjoy the longer lifespan.
Migratory monarchs who survive the journey to Mexico will enjoy the winter in the fir trees there, clustered together with their generation in frequently stunning swaths of color. One of the most beautiful displays of nature to be seen in one’s lifetime certainly would be hundreds or thousands of monarchs fluttering out of a tree at once during their journey. After surviving winter, the monarchs will head back north, landing where the temperatures, milkweed, and need to lay eggs all align.
While how long monarch butterflies live depends immediately on which generations they belong to, all are at risk, as there has been an alarming decline in the number of monarchs migrating each year, and by extension, the number who live natural lives in their native areas. Deforestation and unfavorable weather are two causes of this rather sudden endangerment. The development of land that previously hosted much wildlife has had a massive impact on the monarch, and that’s as true in Mexico as it is in the United States and Canada. The tree canopy that protects the butterflies, the milkweed they require, and the flowers that feed them are disappearing as much as the butterflies themselves are. Southern drought and early northern cold have cut populations drastically as well. If millions of migrating monarchs encounter a large area suffering from drought along their travels, they will not have enough nectar to eat, and certainly no milkweed for any butterfly who is ready to lay eggs.
One nasty development affecting the monarch butterfly and how long they live would be the widespread use of particular herbicides. These herbicides virtually eradicate many native plants that the monarchs and others need to flourish, and as big agriculture grows, it will only get worse. Not only is milkweed in scarcer supply, but so are wildflowers that monarchs, migrating or local, need to pull nectar from to live. The destruction of this delicate, iconic species could be a bad omen of even worse effects of modern life that are yet to be seen, but there are small things that anyone can do to make a little difference and give the butterflies a fighting chance for survival. Planting native milkweed on your property and avoiding the use of herbicides are a great start for all private citizens looking to share the beauty of the monarch butterfly for generations to come.