Mighty monarchs

Monarch butterfly: Image courtesy The Divine Miss K.
Monarch butterfly: Image courtesy The Divine Miss K.
As with the earlier post this question comes from the handwritten questions people leave for our featured Scientist on the Spot. Not all the questions fall into the given scientist’s area of expertise, but are still good questions, so I’m taking a stab at answering them.

This question is particularly timely: “How many days does it take for a Monarch butterfly to hatch?” Timely not only because the migration of Monarchs to Mexico begins in August, but also timely for me on a personal level as one of my favorite places to visit with my mom, wife and daughter at the upcoming Minnesota State Fair is the butterfly tent! (Which, devoted fairgoers, has moved to east of the grandstand on the corner of Dan Patch Avenue and Underwood Street.)

I am assuming the question is really how long it takes the butterfly to metamorphize from a caterpillar to a butterfly. I ask because the caterpillars themselves hatch from eggs. The whole process, from egg to butterfly, takes four weeks. The eggs hatch after 7-10 days, and the process of hatching from the chrysalis takes around two weeks. The length of these stages is impacted by the temperature – the cooler it is the longer this process takes.

Monarch migration patterns: Image courtesy Monarch Watch.
Monarch migration patterns: Image courtesy Monarch Watch.
Now, here is one of the really cool things about Monarchs, I think. Each adult butterfly lives about 4-5 weeks. But once a year in the autumn there is a "Methuselah generation" which will live 7-8 months – effectively outliving the combined lifespan of their parents, grandparents, great-grandparents, and great-great-grandparents. It is this generation of butterflies that migrates from Canada and the United States to either Mexico (if they are east of the Rocky Mountains) or to the Southern California cost (if they are west of the Rocky Mountains – though this population seems to be shrinking – see an earlier post on this).

It is incredible to me that these insects can make a migration that they have never made before, that their parents never made, their grand parents never made, as well as their great-grandparents, and great-great-grandparents. Bryan wrote a post on some recent research that butterflies, “sych UV information up with a natural clock in their brain. By combining these two bits of information, monarchs are able to determine the angle of the sun and always head due south,” which I think is really amazing.

Thanks for the great question!

Your Comments, Thoughts, Questions, Ideas

Liza's picture
Liza says:

If you have milkweed plants in your yard, you can hatch and rear your own monarch butterflies. (We've had quite a hatchery running at our house this summer. We keep bringing in new leaves to feed the existing caterpillars, and then finding new eggs on those leaves, which hatch into caterpillars that have to be fed...)

The tiny eggs are laid on the underside of milkweed leaves. The newly hatched caterpillars start out very small, but they grow quickly. (They have to shed their skin to grow, but you almost never see cast-off skins. Why? They eat 'em.) The caterpillars go through five growth stages, or instars, and look a little bit different after each one. And you know that book, The Very Hungry Caterpillar? Well, it's no exaggeration. These caterpillars are hungry. But they don't eat fruit and sausages and slices of cherry pie; they ONLY eat milkweed leaves. (Monarch life cycle)

When they've eaten all they can eat, they form chrysalises. And they remain there for about two weeks. Eventually, the new butterfly struggles free, dries out for a while, and then flies away to start the whole process all over again.

If you're lucky enough to find a milkweed leaf with a monarch egg on it, bring it in and try raising the butterfly. We keep ours in jelly jars: we put a damp paper towel in the bottom, and replace the lid insert with a small piece of window screening or another paper towel. You'll need to clean the jar and replace the bottom paper towel at least once a day, and probably feed your caterpillar twice a day. (Remember: they don't eat anything except milkweed.) When your caterpillar seems huge, and has developed long antennae, put a stick or something in the jar so it can climb to the top. It will hang from the paper towel or the window screening in sort of a "j" shape. And within a day or so, it will have become a pupa. Pupae are sort of boring, but after about two weeks, the green pupa will turn black, and you might be able to see the pattern and color of a monarch wing through it. That means your butterfly is close to hatching, and if you're lucky, you might see it. (Here's a video in case you miss it; we missed it 8 times this summer!) Once it's hatched, your butterfly needs a few hours for its wings to dry and harden. You should keep it in the jar for at least 5-6 hours, or as many as 24. And then you just unscrew the lid, and watch your butterfly take off on its maiden flight. Very, super cool.

Tons of monarch links

posted on Wed, 08/01/2007 - 2:04pm
Sheridan's picture
Sheridan says:

I found my catapillar up North in Buckhorn Ontario When it was feeding. I decided to take the plant and put him in a jar. And He ate, 24/7. I new soon he would go into a chrystalis. I had to go home. So I took him back with me to my home.

That night I noticed he was hanging upside down. I know what that ment. Chrstalis. So next morning I woke up and of course their he was, in a beautiful green chrystalis. I waited 2 weeks for the colour to change. Last Night I saw that it was black.

I woke up this morning and saw that it was even darker so i knew i would have to take it to my baseball game just incase it would hatch. But just before I was going to leave I hear my dad say " Sheridan! He's Hatching!" I ran down and we watched him hatch. I had to take him to my game and I took him out after he was done drying. He stayed on myfinger and didn't want to leave. He wouldn't fly. But I think he needs a couple more hours today. But also I notice now that their is not one circle on his hind wing. So that must mean. He's a SHE! Pappi ( Pappion (French for butterfly)) Will soon be ready to take her adventure in the Wild.

posted on Sun, 08/26/2007 - 9:24am
Sabrina's picture
Sabrina says:

I bought som milkweed today and in school my class is trying to raise monarch butterflys in class two or three died. I brought mine home today. One is almost ready to turn into a chrstails and one has already been in a chrstails four days already and I hope it will hatch at my house because I think that if I let it go at my house it might keep coming. I really hope it's a girl so it can lay more eggs.

posted on Tue, 05/06/2008 - 3:32pm
Joe's picture
Joe says:

On an unrelated note, I bought some preying mantis eggs for my backyard. They should hatch in a few days which will be totally awesome.

posted on Wed, 05/07/2008 - 8:31pm
Anonymous's picture
Anonymous says:

I love the info on the special generationa and the ablity of the it.

posted on Wed, 01/07/2009 - 6:38pm
Monarch Butterflies's picture

Monarch butterflies are the milkweed butterfly in the family Nymphalidae. It is perhaps the best known of all the North American butterflies. Since the 19th century, it has been found in the New Zealand and in the Australia since 1871 where it is called the Wanderer. In the Europe it is resident in Canary Islands, Azores and the Madeira.

posted on Thu, 12/16/2010 - 1:46am

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