Tropical Milkweed, What is the story?


2016 Update- with more gardeners planting tropical milkweed, the overwintering population in Mexico grew 3.5 times: from 57 million monarchs…to 200 million!

Every time I see a story about Monarchs in the Sentinel, there is usually discouraging information about growing Tropical Milkweed. The theory is that the Tropical milkweed grows later into the winter season than the “native” milkweeds. That longer growth allows the OE infection (Ophryocystis elektroscirrha) to kill the Monarchs. There is much debate about this, I am in the forth year of raising Monarchs indoors, this summer of 2017, I released 57 Monarchs of the 60 I had in chrysalis. Three had disease and didn’t make it. In nature less than 5% of the eggs that are laid become butterflies, so my average is pretty good.

That said, I have branched out with several new milkweeds. In addition to the three types of Tropical Milkweed,  I now grow Swamp Milkweed, Showy Milkweed (native), Narrow Leaf Milkweed (native) and Balloon Milkweed. I have tried for three years to grow the California native, Heartleaf Milkweed, but every year it dies after only growing a few inches. It likes mountainous areas, not here by the ocean.

Important information from the Live Monarch Foundation regarding Tropical Milkweed:

Live Monarch Foundation posts on their website:

Have you seen a warning that Milkweed can hurt the Monarchs or their Migration?: There is an unfortunate campaign underway to change the way you view the world and stop you from taking action to heal it. Science is often misused to make a point that is false or misleading. This is commonly called propaganda ( information, especially of a biased or misleading nature, used to promote or publicize a particular political cause or point of view.) Sadly the Monarch has been caught up in the mix for quite some time. If only they did not migrate through millions of acres of GMO crops or land on flowers contaminated by toxins. But that is not our reality. Please do not be frightened by the scare tactics that tell you some Milkweed is “killing, trapping or harming the Monarchs or their Migration”. Your efforts to plant Milkweed are appreciated by every Monarch that survives the REAL threats to all of us. If you find questionable articles that seem to “spin” the facts about Milkweed and Monarchs please let us know and read our responses to them here. Agribusiness knows that we find their products and actions objectionable and are looking for every opportunity to convince you that these had nothing to do with the Monarch problem.

More responses and Investigations from Live Monarch Foundation:

The Live Monarch staff and our friends will attempt to clarify the commonly used techniques and misinformation about Milkweed and the problems facing the Monarchs and their migration. 

Common myths and false statements about Milkweed and Monarchs:

Anything can be stated as true for a particular set of circumstances but when stated as a truth for all cases this is propaganda = A LIE. Our culture is full of “SPIN” and deception and it is up to you to learn the truth about what people tell you and why. This is work and it takes dedication to understand the methods used to fool you into believing things that sound good are really very bad and sometimes very dangerous. Some examples of corporations that will sell their product no mater what: Cigarettes – Just what the doctor ordered 75% of Doctors Prefer Camels. 7-Up is for Babies. Sugar might be the willpower you need to curb your appetite. DDT is good for you and me. Glyphosate is good for the soil, water and air. Maybe you know a bit about the harmful effects of these products on the actual users, if you do not this is the work I mentioned earlier. This internet is a worldwide library of information and opinions find something other than a sales pitch to fall for. This is a page in progress and will be added to as necessary and of value to our readers.

1. Milkweed kills Monarchs – Is this really true? NO, but in the case of limited milkweed leaves and older plants that have excess toxins that the caterpillars can not digest some larvae may perish. The Milkweed has no Malice and does not seek out victims like the intent of a pesticide. It has been proven to aid the Monarch in many ways and they have a symbiotic relationship that has formed over millennia. Did you know that Asclepias Curassavica has been scientifically shown to be the choice of Monarchs to cure their offspring from paracites. The female Monarch actually searches for medicinal plants for her young. This variety of milkweed is by far the favorite of Monarchs and they will choose it over all others.

2. Non Native Milkweed can hurt the migration – In fabricated scenarios of wayward female Monarchs carrying eggs and being stopped from their migration route by the siren’s call of this milkweed and then the trapping of these larvae on the plants only to die as the cold closes in. Well this Natural pattern of late egg laying and death by weather has happened for millennia and could happen with any milkweed variety depending on location and time of year. Monarchs will not lay as many eggs on less preferred varieties if Asclepias Curassavica is available. Monarchs know what is best for their young, they taste the leaves before laying and do prefer this variety.

3. Tropical Milkweed is a host for OE – No plant is a “Host” for this paracite, it lives inside the gut of the Monarch caterpillar and creates egg cysts while inside the Monarch’s skin as a pupae. During this time it can cover the newly forming abdomen of the adult Monarch with many thousands of its eggs which will be carried by the Monarch and deposited with each egg the female sticks to the milkweed leaves or in rare cases transferred from adult to adult when mating. Milkweed is Not a host and any milkweed could have these egg cysts attached to the deposited egg or dropped by passing Monarchs. Unless confined breeding is underway the eating of cysts dropped by passing Monarchs would be very rare in a natural environment with milkweed growing outside in the wind or rain.

4.Asclepias Curassavica is Not Native – this classic bit of disinformation is true of any milkweed variety depending on where you are. Monarchs look for the best Milkweed they can find. This “Native” Asclepias Curassavica has been in North America over 200 years according to cited records. This is a non issue to the Monarchs and the dangers stated by these articles need to be reviewed and made open for evaluation before warning the public that their actions are problematic. This milkweed is commonly called Mexican Blood flower and is found throughout Texas, Florida, California, Louisiana and Tennessee according to the USDA maps. AND all over Mexico the overwintering home of the majority of all North American Monarchs. Let us not pin the decline of the Monarchs on well intentioned people planting certain milkweeds. This is also the best type of milkweed bar none for collecting eggs.

The way around concern for growing this type in any location is as a just in case food source if and when native varieties run out and to save larvae from starvation. It should like all other milkweed be cut back or brought inside if it would pose a danger for any late season egg laying where knowledge of a severe cold front would kill it and unfortunate monarchs in any stage of their lifecycle.

5. Asclepias Curassavica “does not die back in the winter like native milkweed does” – This is false and it is NATIVE in several southern states. This milkweed dies back with the first frost in most areas, even South Florida. Die back = losing leaves. If you mean dies completely… Curassavica must be replanted each year in areas of hard frost as this plant does not survive a hard winter unprotected. Again it is a great choice if you are in run out of other varieties for any reason and want your Caterpillars to survive and fly away as healthy Monarchs to join the Migration.

6. Monarchs are not migrating when certain types of Milkweed are grown – “But if the monarchs are not migrating, and the tropical milkweed is not dying off, OE never goes away.” Lets use an example of this type of false argument:

If the Homeless are coming to shelters and we are not closing them, poverty will never go away. Rings true if you have no understanding of the real problem. While you are at it shutter all the hospitals as they are just collectors of the sick. This is bad logic. IF THERE IS A PROBLEM, HIDING THE RESULTS OF THAT PROBLEM IS NOT THE SOLUTION. Invest in something that is not a subsidy, Milkweed is a growth strategy. One seed produces food for several monarchs and seeds for the future. There is a geometric progression of benefit for a small investment of effort. This is what Nature shows us. Look for the Natural Example.

THE REAL PROBLEM – for the Monarchs

SAFE PESTICIDE FREE Milkweed is in short supply for the Monarch Migration.


People are turning millions of acres into killing fields through which the Monarchs must pass every year. <


Global change = a situation hastened by the actions of MAN affects every living thing on OUR planet.



Lets stop the UNNATURAL threats to our environment.

Focus on the problem not a symptom!

Posted by the Staff of Live Monarch

Paul Cherubini (posted on says

“It has been hypothesized that the planting of tropical milkweeds at temperate zone latitudes such as along the California coast could have important health and reproductive physiology consequences for diapausing monarch migratory populations:

However, there is a lot of real world case history evidence (e.g. Australia, New Zealand, Spain, Portugal) that diapausing migratory monarch populations have thrived for 50-100+ years solely on tropical milkweed alone. There is one additional case of a tiny island and apparently non-diapausing population much closer to the USA – the island of Bermuda, 600 mile east of South Carolina out in the Atlantic ocean (about the same latitude as San Diego, Calif.)

Bermuda is only 21 square miles in size – less than half the land area of San Francisco. The monarch population there didn’t exist until after the native cedar/palmetto forests were cut down by the arriving european colonists in 1609 to make room for agriculture and settlements and after two weedy non-native invasive tropical milkweeds (curassavica and physocarpa) became established on the disturbed ground: By the late 1800’s monarchs were a common butterfly on the island.

Today monarchs continue to be present on Bermuda despite massive suburban development, decades of inbreeding and decades of being confined to very small amounts of tropical milkweed. There is a monarch conservation group in Bermuda dedicated to conserving the monarch via planting more non-native tropical milkweed: Here is the complete journal article about Bermuda’s monarchs:

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