Milkweed and Monarchs – Finally!

Milkweed and Monarchs – Finally!

Note: See comments below for discussion on native vs tropical milkweeds

We planted a couple milkweed (Asclepius curassavica or tropical) plants three years ago. But – no monarchs or caterpillars. The last six months the milkweed thrived and climbed seven feet up into our magnolia tree, and also spread via seed. Now we have a couple dozen plants out front.

I counted 8, only to check the next day and they were all gone. After all, they look like they were in their 5th instar.

After seeing this guy, I counted 8, only to check the next day and there were none After all, they look like they were in their 5th instar.

One week ago, after a short trip away, I was watering and noticed a huge caterpillar (see right) and then saw more. Yea – finally!

We didn’t have time to enjoy them long as they were ready to go to their next stage. I’ve looked all over for the well-hidden pupa (or chrysalis) – no luck.  In another 3-7 days, we’ll look for the new emerged butterfly, as the chrysalis stage is 10-14 days. In the meantime, we’ve seen more adults (featured photo above) so others are continuing the cycle.

Click here for more on their lifecycle – thank you Monarch Watch.

Update: 11/21/15: Since the post above, we’ve watched another set of caterpillars get fat on our tropical milkweed. We’ve watched them hang into a ‘J’ form where they hang upside down before becoming a green case (chrysalis). One even walked 25 feet up our driveway to another area of plants, and then walked back to a manzanita close to the milkweed patch to form its chrysalis. Apparently, sometimes things are better closer to home. Photos below:

Click here for a post on tips on attracting butterflies and pollinators given by two expert

About Linda Richards

My goal is to educate about the science of nature in layperson speak, through my writing, science and education background. I grew up in the Chicago area, loved living in Minneapolis before gravitating to the West, which is now home.


  1. Marilyn Hempel says:

    In anticipation of planting a large area of natives, I have been doing research on milkweed. I also have planted the Asclepius curassavica, but it turns out that is not a So Cal native milkweed. It’s from South America and is therefore not as good for our monarch butterflies. Read the quotation from Las Pilitas nursery below. According to them I should remove the milkweeds I have planted and put in the true natives. Right now you can buy the natives at Las Pilitas and at the Rancho Santa Ana Botanic Garden.

    “Alkaloids from the wrong milkweed (South American, Mexican, etc.) can expose butterflies to predation. If the monarch or other butterfly has not evolved with the milkweed they may have limited tolerance for the particular alkaloid or latex of the plant species. The California flyway runs from Baja to Canada, it does not include Mexico proper nor Central America. If you live in Chicago you can plant Mexican species (Asclepias mexicana) or Asclepias tuberosa, don’t plant our species. Don’t plant Mexican or South American milkweed in southern California.”

    • I know Butterfly Farms sells many varieties, including the tropical curassavica, and they have a different viewpoint. I’ll check further because what you say make sense – and I prefer plants native to your area. I wish my native ones had survived — but will try again. Thanks…

      • Hi all – here’s some input from Tom Merriman from Butterfly Farms in Vista CA, which grows milkweed varieties for Rancho Santa Ana Botanic Garden, Monarch Watch, Resource Conservation Districts, schools, institutions and the general public.

        “We encourage native plantings but also grow some exotic species, such as the tropical.

        Las Pilitas has an awesome website but is not always correct. We use tropical milkweed for a food plant to raise butterflies here. It is actually the preferred plant for Monarchs, gravid females will pass over native to lay on it and I have watched caterpillars crawl off of native onto the tropical. It actually has a higher concentration of the toxin that protects Monarchs from predation. It can actually kill the protozoan (OE) and heavily infected Monarchs will seek it out.

        There is conjecture that tropical milkweed planted in the eastern flyway may impede the migration or create higher incidence of OE. There is no science behind this and is being studied now. Neither Xerces or Monarch Watch has weighed in on this.

        So right now the science is that tropical milkweed is good for individual Monarchs but MAY be detrimental for them as a whole. Some native plant enthusiasts will tell you it is invasive and bad for Monarchs but the science just isn’t there.”

        Finally, Tom provided this interesting article ‘What You Should Know about Monarchs’ by butterfly expert Al Shapiro –

        For people wanting more research on monarch diseases – he cited this paper, published in J Chem Ecol (2015) 41:520–523, which I would be glad to forward to anyone.
        Secondary Defense Chemicals in Milkweed Reduce
        Parasite Infection in Monarch Butterflies

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