Why did the little boy throw butter out the window? He wanted to see the butterfly! OK…that’s an old joke you’ve probably heard many times. But who doesn’t like to see butterflies?
Butterflies always fascinate children, because of the miraculous transformation they go through during their life cycle. It’s simply incredible that those unusual caterpillar bugs can change into beautiful butterflies.
One of the joys of sunny summer days is watching butterflies float around the backyard. As they flit from flower to flower, they seem so delicate. Would you believe, though, that butterflies can actually fly incredible distances?
One particular butterfly species — the Monarch butterfly — travels great distances every year during its annual migration. Summer in North America is usually nice and warm, but Monarch butterflies can’t survive the cold winters of most parts of the United States.
Each year around October (or earlier if it turns cold earlier), Monarch butterflies migrate south and west to find warmer weather. Monarch butterflies from the Eastern United States travel to Mexico, while butterflies that live west of the Rocky Mountains head to California.
Amazingly, Monarch butterflies travel to the same destinations every year. How long is the trip? For some Monarch butterflies, the journey can be as long as 2,000 miles and take up to two months to complete. Isn’t it cool that something so beautiful and delicate could travel so far?
The story doesn’t end there, though. It gets more incredible. Because the life span of Monarch butterflies is fairly short (6-8 weeks), it’s actually subsequent generations of Monarch butterflies that make the same trips each year.
Most insects do not migrate, because their life spans are not long enough. Only Monarch butterflies born in September and October survive long enough to migrate. The butterflies that travel to Mexico and California have children — and sometimes grandchildren! — that then make the return trip in the spring.
How do they do it? Scientists believe they use a sophisticated system they call a time-adjusted sun compass. In other words, they follow the sun. Because the sun is always moving, though, this isn’t as easy as it sounds.
Monarch butterflies have a 24-hour internal clock — called a circadian clock — that is part of their antennae. This part of the system tells the butterflies what time of day it is. Depending upon the time of day, the butterflies can then tell approximately where the sun should be.
The butterflies then use special photoreceptors inside their eyes to follow the angle of the sun. Incredibly, Monarch butterflies are able to pass on these innate directions to their children and subsequent generations. Isn’t nature WONDERful?