Monarch Caterpillars, Milkweed and WWII


There has been much concern about the dwindling  numbers of Monarch Butterflies.  An organization called Monarch Watch has been encouraging everyone to plant Milkweed, also know as Butterfly Weed.

I have been planting Butterfly Weed all over the yard.  Unfortunately, a beetle has shown up the last few years and has eaten almost all the plants I grew.  This year I am trying to collect the bugs daily for disposal, as any kind of spraying will also kill the Monarchs.

I was pleased to find many very fat and healthy Monarch Caterpillars on the Butterfly Weed.  This one is eyeing his competition.


My main purpose for planting Butterfly Weed is to feed caterpillars.  The plants tend to look pretty bad after awhile.  Interestingly, the plants contain a chemical called cardiac glycoside that cause birds to vomit.  By eating the leaves, the caterpillars are protected from birds.

I find that rabbits and deer also avoid the plant. The most common Butterfly Weed grown here is Asclepias tuberosa, which is tropical/Mexican Butterfly Weed.

The plants produce seed pods filled with seeds attached to fluffy floss that allows them to drift in the wind to a new location.

I recently found out that Milkweed floss had an important role in World War II.  School children from all over the country were sent out to collect the seed pods to make life vests for Navy sailors. Milkweed in the northern U.S. is much larger than the ones that grow in the South and were found growing in fields and along the roads.  The seeds were removed and the floss was used to stuff the vests.

I find it hard to imagine that these vest would stay afloat for long, but I guess that is what they had back then.  While researching, I also found an article with instructions for making a down-like coat using the Milkweed floss for the insulation.  As it turns out, this “weed” is not only necessary for Monarchs, but humans have also found uses for it.

21 Comments on “Monarch Caterpillars, Milkweed and WWII”

  1. Christina says:

    Fascinating, and great that you already have some Monarch caterpillars.

  2. Tina says:

    Great post and photos, to boot! I didn’t know about the life vests, very interesting. I saw a couple of monarchs through my garden weeks ago and one monarch cat on a milkweed, though I haven’t seen him/her since. I’ll keep looking though–I’d love to catch an emergence!

  3. Interesting post, Ms. Gardener. Thanks for sharing.

  4. I had Hairy Balls Milkweed last summer and will try to find yours this season. It sounds like northern Milkweed is like Kapok.
    I saw one caterpillar and a few Monarchs here.

  5. shoreacres says:

    I’m going to have to do some research myself. I know I’ve read that your milkweed — the tropical milkweed — isn’t recommended. I haven’t a clue why, although it seems I remember that its longer bloom keeps monarchs from migrating. But, it might have been something else entirely. When I get an extra minute, I’ll try to figure it out.

    I was in the hill country recently, and was astonished by the amount of milkweed around. I finally figured out that our green antelope horn isn’t the same as “their” antelope horn. There’s so much to learn — and I’m easily confused!

    I did see a lot of monarchs in Brazoria County on Easter. It’s rare that I see more than one or two, but it certainly looked like a migration. Good for you for feeding these little beauties. It’s just so admirable — good for them, and good for those of us who love seeing them, too.

    • The tropical is the only one I have luck with. Maybe it likes my heavy clay soil. Years ago I was at San Luis Pass in the Fall and saw a lot of Monarchs on a bridge (or over pass). They may pass through that area on their way to and from Mexico.

      • shoreacres says:

        I found the article I was remembering. You can read it here.

        And, I figured out the confusion. Your Asclepias tuberosa is called butterfly weed, or tropical milkweed, but the same common names are applied to Asclepias curassavica, the milkweed that seems to be of questionable value for the monarchs.

        Thank goodness for scientific names, that’s what I say. They do help sort things out from time to time!

      • I am not really good with the scientific names, but I will look them up if needed. I have also found many plants have similar common names or they actually change depending on the vendor. Thanks for the article.

  6. Sheryl says:

    It’s fascinating how milkweed was used in life vests during WWII. I can remember having a couple life vests that were filled with kapok (which I think comes from the seed pods of another plant) years ago.

    • Apparently, they could not get the kapok at that time, as it was from the Pacific. I first heard the story in PA and we loved to collect milkweed from the fields there when we were kids.

  7. What an interesting post! I knew about Milkweed, but didn’t know all that other stuff about Monarchs.
    A week ago, on a warm-weather day, we had two Monarchs in our garden and I couldn’t believe they could be that early. So my husband took photos, and sure enough, they were.

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