The Amazing Life of the Monarch Butterfly
Monarchs, like all butterflies, go through a 4 stage life cycle. They begin as eggs, hatch into caterpillars, enfold themselves into a chrysalis as a pupa, and while inside metamorphose (which means to change shape) into a striking orange and black butterfly. One thing that makes Monarchs unique is that their caterpillars will only eat milkweed plants, and will starve without them. Eating milkweed provides them protection from many predators, as the caterpillars and butterflies concentrate toxic chemicals (cardenolide alkaloids) found in the milky sap.
Another thing that makes Monarch Butterflies unique in the insect world is their annual migration. Monarchs that breed in eastern North America migrate up to 2,500 miles to wintering sites in Mexico. Monarchs that breed in western North America migrate to the California coast for the winter. That is a long way for a creature that has a wing span of 4 inches and weighs 500 grams (equivalent to a paper clip)!
(Click on any of the images to get a closer look)
The lifespan of a monarch butterfly is short, though the generation that overwinters in Mexico and California lives up to 8 months.
In the fall Eastern Monarchs fly south to overwinter in special forests in Mexico. The Western population overwinters along the California coast. In the spring and summer Monarchs either fly north from Mexico to the U.S. and Canada, or move inland and north from the California coast.
Numbers of Monarchs are Declining
Unfortunately, the things that make Monarchs unique are also posing challenges to their survival. Their overwintering sites in Mexico and in California are threatened by development and habitat loss. Another threat to the species is the huge decline in milkweed plants found in the United States and Canada, due to habitat loss from human development and the expansion of agriculture (particularly crops that have been genetically modified to resist the pesticide Roundup). Milkweed, which used to grow alongside crops like corn and soybeans, has almost disappeared from Midwestern fields. This loss of habitat for their host plant, along with periods of bad weather in the forests where the butterflies hibernate in Mexico, have severely reduced the numbers of Monarchs.
Help Monarchs by Planting Milkweed
The news is not all bad though. Recognizing that the Monarchs’ dependance on milkweed that is disappearing is endangering this iconic butterfly, people all over North America are doing what they can to help. From pushing for protections for their overwintering grounds, to the very simple step of planting lots and lots and lots of milkweed.
You too can participate in helping Monarchs, by setting up a sanctuary in your yard, garden, school, or business. Your reward will be the countless butterflies that flutter through your yard, feeding on your plants and also laying eggs. You will get to watch monarchs first hand as they progress through the stages of their lives. Check out these amazing moments I have witnessed in my yard over the past 2 years…
Monarch butterflies laying eggs. They bend their abdomens up and lay eggs on the underside of leaves or on flower buds. The eggs are the small white dots in the lower panels. In the panel on the left you can see some tiny hatchlings.
Big fat Monarch Caterpillars. These guys can chew through a leaf so fast!
Monarchs leave the milkweed plant when the pupate. Sometimes you find their chrysalises out in the open, but often they are hidden away. The chrysalis starts out bright green, and then becomes transparent. The unique orange and black pattern can be seen through the thinning walls of the chrysalis when the butterfly is close to emerging.
Monarch butterflies love to feed on milkweed nectar, but they also enjoy feeding from other flowers. Be sure to have lots of different food sources for them in your sanctuary.
Growing Milkweed in Your Yard or Garden
You will probably find that, just like eating potato chips, you can’t have just one milkweed plant. I started with one, and now have several scattered around. My main patch is a collection of 5 large pots, and I have three or four other areas in my yard. I have mainly tropical milkweed (Asclepias curassavica), though I recently started a batch of narrow leaf milkweed (Asclepias fascicularis), a California native. The milkweed that you mainly find in nurseries in CA is tropical (Monarchs really like laying their eggs on this one), but you can purchase seeds of native milkweeds over the internet or you can find plants at native plant nurseries.
My main patch of tropical milkweed on the right; tropical (in the pots) and narrow leaf milkweed (in the seed starter) plants I am growing from seeds.
Some of the many species of milkweed that are native to California, plus one random non-native that I put in because it is so pretty!
Once you have healthy milkweed plants growing, getting more is easy! They produce many seed pods, and you can harvest the seeds before they blow away and plant them. I use 72 well seed starters that you can get for under 10 dollars. I also just shove seeds into the dirt in random pots around my yard and wait for little milkweeds to grow. One thing to be careful of is that rodents love to eat milkweed seedlings, so when I use seed starters I make sure to put the cover on them and keep them up high when the seedlings are young and tender. If you generate too many seeds to plant yourself, you could give them away to friends, or send them into seed collecting programs that you can find online.
Milkweed seeds blowing away from a seedpod. On the left are seeds that have not fluffed out their floss yet. They are really beautiful!
Sam planting milkweed seeds in a seed starter. He planted 100 seeds, and 40% of them germinated. Once the plants were bigger he gave them away to his Boy Scout troop.
Maintaining Healthy Plants
One thing that you cannot do is get attached to a leafy, lush milkweed plant. Because if you get lucky and have a bumper crop of caterpillars, they will eat it down to nothing. It is a good idea to have a backup plan, in case all of the leaves are eaten. I have twice carried containers of caterpillars over to a local garden when my caterpillars ate every single leaf off of my original plant. This is also how my collection grew, as I ran out and bought several more plants as insurance against caterpillar famine! There are a few pests you want to keep an eye out for. You will find yellow aphids on your plants. I squish them with my fingers, sometimes also washing them off using a soapy solution (mix a few squirts of dish washing liquid with water and keep in a spray bottle) or the mist setting on my hose nozzle. If you have a lot of ants around the base of your plant, carefully spray a little ant killer. Ants milk the aphids like cows, so you don’t want too many ants on your plants. Or in your pants. You also want to pluck off and kill any black and red milkweed beetles you find, as they suck the life out of the seeds in the seed pods. Finally, if you see whitish, sick-looking leaves, remove them, and also scrape off any scale insects you see, which look like little brown limpets clinging to the stems and branches of the plant. Some people suggest that you cut back your tropical milkweed in the fall if you live in a climate like California where it thrives and blooms year round, to reduce plant diseases and to encourage monarchs to continue their migrations. I don’t really do this. I hope the milkweed militants don’t find me…
My original milkweed that was chewed down the sticks. It recovered in a few weeks, and was bushy and healthy again in no time.
These creepy little yellow aphids will suck your milkweed dry if you don’t remove them.
These red and black milkweed beetles suck the juices out of the seeds in the seed pods, which ruins the seeds. Have no mercy, even on the little ones.
Monarch Predators
Even though they are poisonous to many creatures, some are able to eat Monarch Caterpillars and Butterflies. Mice, assassin beetles, and some species of wasps, spiders, and birds are known predators of Monarchs. I have seen caterpillars fleeing from a milkweed plant, so if this happens check on the stems and the underside of leaves for any other insects. I have very low tolerance for any insects on my milkweed plants, and the only ones I let live are lady bugs.
Wrap Up
For more information, please visit these websites (from which I obtained many of the facts in this post).
The Monarch Program
Monarch Watch
Monarch Butterfly – Journey North
USDA Forest Service – The Monarch Butterfly in North America
I hope that I have convinced you to take the plunge into milkweed and Monarch madness. You will not regret it, as you welcome these wonderful creatures into your life. If you still aren’t convinced, check out these amazing videos I took recently in my yard.
A Monarch Butterfly laying eggs on my milkweed plant
A Monarch Caterpillar eating a milkweed leaf
A Monarch Butterfly feeding on milkweed flower nectar