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Dangers to the monarch butterfly and how to grow milkweed plants as food for monarch butterfly caterpillars

Updated on November 10, 2016

Monarch butterfly caterpillar

Monarch caterpillar on milkweed
Monarch caterpillar on milkweed | Source

Bad news for the Monarch Butterflies

Monarch butterflies are experiencing terrible problems in America and the numbers arriving in Mexico to overwinter have been at a record low. This news has been reported by the mainstream media, including National Geographic.

But good people who are concerned about the survival of these amazing and much-loved butterflies are doing what they can to help them. This is happening throughout North America and elsewhere in the world. A lot of people want to help the monarchs survive. Growing milkweed for the caterpillars is one of the best ways.

Monarch Butterfly

Adult monarch butterfly
Adult monarch butterfly | Source

Monarch butterfly poll

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Threats to Monarch Butterflies

Known threats the monarchs include the use of pesticides and herbicides, habitat destruction and Climate Change.

One serious problem they are facing is lack of the food-plants for the caterpillars. They are able to eat any species of milkweed (Asclepias).and under normal conditions, as they once were, these plants were commonly found all the way up from the southern States up as far as Canada.

Different species in the milkweed genus are able to grow in the different climatic zones. Sadly large areas devoted to farming now grow Roundup Ready genetically engineered crops that are sprayed with the herbicide Roundup. This has killed off vast amounts of milkweed that used to grow in the fields where they crops, such as maize and soya, are planted.

If that wasn’t bad enough, it is said, that airborne pollen from these crops that lands on milkweed that has survived and that has caterpillars on, will kill them because of the toxins genetically engineered into it to be resistant to herbicides. This has not been adequately studied though.

However, it is definitely agreed that there are far fewer milkweed plants about now. So the supply of food for the larvae has been drastically reduced. It is estimated that this reduction is as much as 58%.

Another problem is that forests that they used to roost in in Mexico have been cut down.

Extreme weather conditions have taken a heavy toll as well.

Why fewer monarch butterflies are surviving their winter migration

Monarch distribution elsewhere in the world

Monarch butterflies at this stage are not regarded as an endangered species because they are found in many countries around the world besides America,

However, what is currently is endangered is their spectacular migration route from Canada and the States in the most northerly parts of the US down to Mexico for the winter and then back up the country again the flowing year.

This fantastic migration has been recognised as one of the real wonders of nature and has made the monarch butterfly world-famous for its ability to do this.

Pen for growing Milkweed for Monarch Butterflies


Pens with Milkweed plants


Closeup of corner of a pen for monarch caterpillars and milkweed

Showing construction of the corner of a pen.
Showing construction of the corner of a pen. | Source


Asclepias curassavica the Tropical or Scarlet Milkweed
Asclepias curassavica the Tropical or Scarlet Milkweed | Source

What can be done to help Monarch Butterflies?

People in America have been helping the monarchs by planting more milkweed. The seeds are readily available from Internet suppliers and on Amazon and eBay. There are species that will grow in the different climate zones too.

A big problem that people who cultivate milkweed for the monarch caterpillars is that the larvae will eat so much food that they will strip the plants of leaves, flowers and seed-pods. If insufficient plants are grown to feed a growing army of these large and striped larvae then many of them will starve to death.

So all people who grow milkweed must grow as much as possible and find ways of helping the plants regenerate, which they will do in a short space of time if not subjected to another attack by hungry caterpillars.

The answer to this is quite simple and Lawrence Chapman from Tenerife in the Canary Islands where the butterflies also live and breed has come up with a brilliant idea. He has created pens that can be placed over a garden plot on which milkweed plants have been growing.

The pens stop more female monarchs getting access to the plants to lay their eggs. This means that plants that have already been stripped of leaves by caterpillars can be covered by a pen and allowed to grow back again. The pens are made with a wooden frame and covered with gauze mesh making them easy to make and lightweight so they can be easily moved.

To make a monarch food-plant pen you need: straight lengths of wood 2 cm by 1 and half cm, small brackets from a hardware store (about 1 inch ones) and a pack of plastic netting as well as a staple gun. You can make them to fit with the room you have. A good size for the average garden is 1 m long 80 cm high and 90 cm wide. This can be easily lifte and moved around.

After eating enough leaves the caterpillars spin a small pad of silk either on stems of the plant or on a fence, wall or under garden furniture. They hang head downwards and change into a mint-green chrysalis after changing their skin for the last time as larvae.

The butterflies emerge 10-days to two weeks later depending on temperature.

It is a marvellous experience to watch the transformation from egg to butterfly and to know you have played a role in helping the survival of this beautiful butterfly.

Monarch butterfly chrysalis

Monarch butterfly chrysalis nearly ready for the adult to emerge.
Monarch butterfly chrysalis nearly ready for the adult to emerge. | Source

© 2014 Steve Andrews


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    • Bard of Ely profile image

      Steve Andrews 2 years ago from Lisbon, Portugal

      Thank you so much for sharing this and your comments! Everyone who can do something about getting more milkweed back in America is helping the monarchs!

    • Phyllis Doyle profile image

      Phyllis Doyle Burns 2 years ago from High desert of Nevada.

      This is a very useful, informational article that needs to be shared and shared and shared ! If I had my own yard, I would definitely take on the mission of helping to save the Monarch by growing milkweed. I live in a migratory zone (Washoe Valley, Nevada, USA). I will check the Monarch migration path and milkweed growing zones to see if buying and spreading the seeds on the little mountain range by me will help.

      Thank you for this great hub. Voted Up, across and shared all over the place.

    • Bard of Ely profile image

      Steve Andrews 2 years ago from Lisbon, Portugal

      Because they are the only plants the caterpillars can eat their distribution and numbers depend entirely on how many milkweed plants are about and this I saw clearly in Tenerife where the plants are not native. Unless gardeners grow milkweed there the butterflies could not survive.

    • pagesvoice profile image

      Dennis L. Page 2 years ago from New York/Pennsylvania border

      I noticed last summer that we only had a few monarch butterflies when we normally had many. You are correct about milkweed plants. As a kid walking through the fields they were abundant and our clothes would be covered in the milkweed secretion. Amazing how few of these plants I now see.

    • Bard of Ely profile image

      Steve Andrews 2 years ago from Lisbon, Portugal

      I am so glad you are helping the monarchs too! thank you for commenting and sharing! My friend Lawrence Chapman came up with the brilliant idea for those pens. They are easy to make and so useful!

    • mary615 profile image

      Mary Hyatt 2 years ago from Florida

      I never heard of these pens before! Raising Monarchs is one of my hobbies. I buy Milkweed plants and I enjoy watching the Monarchs hatch out, dry off, then fly away.

      Insecticides used on our roadways are killing off the wild Milkweed where I live.

      I wrote a Hub encouraging people to grow Milkweed in their gardens to help preserve these beautiful butterflies.

      Voted this Hub UP, etc. and shared.

    • Bard of Ely profile image

      Steve Andrews 3 years ago from Lisbon, Portugal

      Hopefully some of those butterflies can find the gardens.

    • Easy Exercise profile image

      Kelly A Burnett 3 years ago from United States

      I have always wanted to plant milkweed and also "buy" some butterflies. What a great and expansive hub to help me. Sadly, I often see "butterflies for sale" for weddings not gardens and yet the gardens are where we need these delightful creatures the most.

    • Bard of Ely profile image

      Steve Andrews 3 years ago from Lisbon, Portugal

      So glad you are saving the milkweed! I hope some monarchs come your way!

    • Ericdierker profile image

      Eric Dierker 3 years ago from Spring Valley, CA. U.S.A.

      Ah ha! we are doing spring weeding. And I put up the big flag! Thank you so much for this article. Our milkweed plants will be left alone and nourished. I thought it was the Mallow, but in there is the Milkweed.

    • Bard of Ely profile image

      Steve Andrews 3 years ago from Lisbon, Portugal

      Thank you TurtleDog!

    • TurtleDog profile image

      TurtleDog 3 years ago

      Wow, great post. Great pictures too. I love the pen construction and I'm impressed with how pretty (for lack of a better word :-) the monarch caterpillar is. Good post and great way to preserve a beautiful insect. up and interesting

    • Bard of Ely profile image

      Steve Andrews 3 years ago from Lisbon, Portugal

      I am so glad you are doing what you can to help them too!

    • kj force profile image

      kjforce 3 years ago from Florida

      Bard of Ely...great hub...very informative...My G-C and I are avid Butterfly lovers...we have many times found caterpillars in my " weed" garden ( native plants) and provided shelter/nutrients until they became a Butterfly...before releasing them, we offer drops of gatorade , usually punch flavor on a small branch..In the summer we provide a small container for them...they will land on your hand and drink also...thanks for the share..

    • Bard of Ely profile image

      Steve Andrews 3 years ago from Lisbon, Portugal

      Thank you for posting, Sally! They should be very comon and could be if they had the food-plants. It is actually that simple.

    • Bard of Ely profile image

      Steve Andrews 3 years ago from Lisbon, Portugal

      Eric, no the caterpillars can only eat milkweed. The adults can take nectar from many flowers.

    • sallybea profile image

      Sally Gulbrandsen 3 years ago from Norfolk

      So nice to find that many people are making the welfare of our Butterflies an important issue. This is one of the most beautiful and extraordinary of butterflies - the caterpillar too. I look upon my encounters with them as being far and few between - it would be lovely to see more of them in my area.

      Thanks for helping to make the public aware of the importance of our Butterflies. Voted up.

      Best wishes


    • Ericdierker profile image

      Eric Dierker 3 years ago from Spring Valley, CA. U.S.A.

      Do they eat/use Mallow also? We have a bunch come through and they seem happy on our Mallow plants.