Runmede, I just posted about the connection between a milkweed's chemical markers and the Monarch's chemical markers, and how those two things are important to tracing the Monarch's migration.

Have you any information about the validity that it's best to plant natives so as not to confuse those chemical markers. With these markers scientists hope to be able to zero in on the migratory path so that they know where to focus restoration efforts.

Are there any worries about the plant becoming invasive anywhere?

A study that I participated in--I collected and sent Monarch specimens and milkweed from my area was looking at stable-carbon and -hydrogen isotope measurements to match milkweed with Monarchs. I don't take butterfly specimens for collections, but do believe in scientific research so when they asked for people to help with their research I did. Three of my specimens were used. The results of that study are listed in the link at the bottom of the page.

6/25/11 -- from Texas collected in Northern VA
6/30/11 -- from Illinois/Indiana collected in Northern VA
8/10/11 -- from Iowa/Missouri/Illinois/Indiana or Ohio collected in Northern VA

I asked the scientist who collected this data about how tropical milkweed interfered with his study and he said it would not be a problem. I thought that tropicals would be a major problem because they are widely used by butterfly farmers, too.

I also participated in an earlier study by the same lab, by sending in a few Monarch specimens and milkweed that were captured/collected in my area.

Monarch butterflies cross the Appalachians from the west to recolonize the east coast of North America

Both studies were accomplished even thought there are tons of tropical milkweed planted in the United States and Canada.

Tropicals are considered invasive in 48 states in the United States. They are present in five states CA, TX, LA, FL, and NC and absent in the other 42 states according to the USDA map.
USDA Plant Database for Asclepias curassavica.
But, remember just across the border in Mexico, they are native. For example in South California, I just read a study by a senior high school student that said in the area (5 mile area) she was studying that tropicals made up 94% of the milkweed species. Get rid of all the tropicals and you would have very little milkweed for the Monarchs that are declining because of the lack of milkweed in many areas. I have consistently recommended in areas where the plant grows year round that it be cut to the ground. I have also recommended that people plant more natives, which can take 2-3 years to become established.

The Prevalence of Ophryocystis elektroscirrha Infections in the Monarch Butterfly (Danaus plexippus): A Study of the Protozoan Parasite in a Wild Population of Western Monarchs.

Here is a link that might be useful: Tracking multi-generational colonization of the breeding grounds by monarch butterflies in eastern North America

You're right, Tropical is found in Southern California in abundance (and so are diseased monarchs) because Tropical is all the big box stores and nurseries sell here and nationwide. Also online Tropical milkweed selling sites erroneously promote Tropical as a "native plant', as a 'fav+rite fo+d', and even denigrate native milkweeds.

NO monarch advocate expert, researcher or ecologist promotes planting tropical milkweed-they discourage planting it and all non-native milkweeds. Altizer clearly links tropical milkweed to OE disease and unnatural overwintering behavior (ceasing to migrate) which is (was?) the monarch's way to cull disease out of their population (via migration).

Is the above post suggesting that because Tropical MW is found growing somewhere, say San Diego, that it can't be removed and native planted? I had diseased wild monarchs in my So Cal yard all year, and the eggs and caterpillars that I took indoors to help out emerged 95% as diseased butterflies and had to be destroyed. it's because my area has become non-migratory due to the abundance of the non native tropical, and the butterflies have become highly diseased. I won't be growing any milkweed next year because I live in the middle of a diseased population.
Removing tropical, re-introducing native milkweed, and creating new native milkweed habitats nationwide--in the cities and the wild, is the only way to save the monarchs. My native milkweed cannot change the fact that tropical is dominating because it was planted and spread. Now tropical is becoming invasive even into central Ca.

The native milkweed from No. Cal to No. Mexico, ID, UT is
A. fascicularis, common names- Mexican whorled milkweed, and Narrowleaf milkweed.

Education is needed. Tropical has clearly been shown to be contributing to the demise of the monarchs, and is also highly invasive and destroying native echosystems and habitats.
How could it be controlled and "cut down" in the winter in milder climates when it is growing all over, in vacant lots, in undeveloped areas, in the wild where no one lives? By the winter, many millions of seeds have come off the plants for 4-5 months and have been carried by the wind to undeveloped areas, where there will be no one to cut it down. Tropical is being considered for the "Invasive species list" in Florida, but it needed to be on that list years ago. It's too late, I'm afraid, has naturalized in many warm winter states.

Link below with photos of A. fascicularis and a beautiful and fun interactive satellite map. This is the native milkweed for the San Diego area mentioned, and most of California and No, Baja, also portions of ID, UT and NV.

Here is a link that might be useful: Asclepias fascicularis MEXICAN WHORLED MILKWEED

The USDA link above, why is it being posted AGAIN? It was posted so many times on the brainstorming site and it has nothing to do with the text it's posted in between.

This link shows that Tropical was introduced to the lower 48 states, introduced to Hawaii, introduced to Puerto Rico, and introduced to the Virgin Islands. So that means it was never a native of North America, and it was never a native of Central America, it was introduced there too.

USDA Link above shows a map of the US and:

Native Status: PR I
L48 I
VI I
HI I

Tropical is native to Mexico. Some of the Monarchs that migrate to the Mexico reserves have OE. Even native milkweed contribute OE spores to Monarchs. It's not the milkweed, it's the OE.

Did you read the article that I posted? If not, the message was that the science is still not there on tropicals. BTW, that scientist in that article works with Dr. Altizer of Project Monarch Health. The article/video on the medicinal value of tropicals was Dr. Altizer's husband.

The science is still out on tropicals. You can do what you want. I'm going to give Monarchs what they need--as many milkweed species as I can plant including tropicals.

"North America, the planetâÂÂs 3rd largest continent, includes (23) countries and dozens of possessions and territories. It contains all Caribbean and Central America countries, Bermuda, Canada, Mexico, the United States of America, as well as Greenland - the worldâÂÂs largest island."

Please refer to the United States and it's territories as the United States. It is not North America.

Here is a link that might be useful: Information on North America

There are two USDA websites, one is world wide and the other is for the United States and Canada.

I was answering bernergrrl on where tropical is invasive in the United States.

I hope you understand now that tropical is native to Mexico, Central America and a bunch of other places, which are in North America. Frankly, native tropical milkweed grows right across the border in Baja, Mexico, which is below Southern California.

The USDA Map in the link that I included only covers the United States and Canada so it would not show Mexico or Central America or cover North America, which is a continent with 23 countries.

It not the milkweed species its the "stable-carbon and -hydrogen isotope measurements" for different areas of the United States. Common and Showy Milkweed grow in many states in the United States and Canada.

So no need to worry about planting tropical milkweed, which is native to Mexico, Central, and Latin America, which is part of North America. It will not interfere with any migration studies.

Thank you. Hopefully science will soon narrow in on the exact causes of the decline of the Monarch, and maybe we can all better concentrate on the best way to save those butterflies. I'm concerned about other butterflies also. Other kinds seem to be declining and there isn't the same emphasis on finding out what's going on with other butterfly species. In my area, drought has been a big factor. When the plants die from drought or wildfires, or water restrictions discourage people who want to grow butterfly gardens, it's bound to affect the butterflies. I still remember the year of the seriously widespread drought/wildfires in Texas. Birds came to my place in the late summer and early fall that I hadn't seen before. Plants and butterflies here were disappearing at an alarming rate. Some species of butterflies have recovered in population numbers here, some still haven't. GMO crops, pesticides, loss of habitat, all those could be caused by actions of humans.

I was looking for info on milkweeds and cardenolides and came across an article which had this paragraph, very interesting (although it's rather a highly technical article, hard to understand, sorry):

It is interesting that two cardenolide forms, calotropin and its configurational isomer calactin (Seiber et al., 1980), are apparently favored among the plantsâ cardenolide spectrum with respect to sequestration or storage (or both) by D. plexippus.
Both of these compounds are the dominant cardenolides stored by the monarch when the caterpillars feed on A. curassavica or A. fruticosa (Seiber et al., 1983; Groeneveld et al., 1990a). Again, calotropin and calactin are the only cardenolides present in the defensive spray of the pyrgomorphid grasshopper P. bufonius
(von Euw et al., 1967). This might mean that calotropin and calactin are at the same time favored by cardenolide carriers, and that they are products of insect metabolism, as demonstrated by Seiber et al. (1980). These compounds, which are some of the most effective cardenolides to induce animal emesis (Duffey, 1977), could in addition possess advantageous properties for storage (Seiber et al., 1980), or avoiding of autointoxication.

Here is a link that might be useful: Toxic cardenolides

In other words Monarch caterpillars eating both of those tropical milkweeds are more toxic to predators. More toxic butterflies provide more protection to those butterflies who are less toxic because predators associate them with more toxic butterflies. For example, common, showy, and butterfly weed milkweeds are lower in toxicity than tropicals so less toxic milkweeds would provide less protection.

Dr. Anurag A. Agrawal is helping me with a milkweed stem weevil problem that I have been having in my yard. The stem weevils have decimated many of my milkweed plants.

Here is a link that might be useful: Milkweed Weevil and Swamp Milkweed Bug

There are many, many people who love to watch butterflies as they flit through the air slowly and gracefully. If you never have, you certainly should! Butterflies provide beauty in an often ugly world. They give us insight into the world of nature and how wonderful and complex it is. But the butterfly is much more than that.
Butterflies are some of the most beautiful and interesting creatures on Earth. A butterfly garden is an easy way to see more butterflies and to help them, since many natural butterfly habitats have been lost to human activities like building homes, roads and farms. It is easy to increase the number and variety of butterflies in your yard.
Creating a butterfly garden should start with some serious research to learn which kinds of butterflies are native to your area. You can learn that from this book âÂÂAttract Butterflies To Your GardenâÂÂ.
Here are some points you should focus:
A. Make a list of all of the different kinds of butterflies you would like to attract, and then learn which flowers and plants they both feed on and lay eggs on.
B. Plant the âÂÂButterfly Host Plantsâ to lay their eggs on.
C. You can add some butterfly garden accessories like a Butterfly House, which has slots the ideal size for keeping birds out while giving butterflies protection from the wind and weather, and are beautiful garden decorations. You could offer an additional nectar source close by to supplement your flowers.
D. Once you have designed and started your butterfly garden, you can be proud that you have made a habitat for butterflies in your own yard, which helps with the conservation of the many species of quickly disappearing butterflies today. You will certainly want to place your favorite outdoor furniture near so that you can enjoy all of your visitors day after day.

Here is a link that might be useful: Attract Butterflies To Your Garden

There is now peer reviewed research showing tropical milkweed in the southern US is BAD news for monarchs.

'The work proves âÂÂabsolutely definitivelyâ that tropical milkweed is threatening the monarchs and their migration, Brower says. And the findings are particularly troubling for monarchs returning from Mexico in the spring, he adds. They pass right through these winter breeding sites and could lay eggs on infected milkweed while they are there or mate with infected butterflies. Infecting the returning monarchs with OE âÂÂis the last thing we want to do, particularly when the monarchs are in the low numbers that they are now,â Brower says.'

And I'll stick with my opinion that the plant should not be planted anywhere in the US where migratory monarchs are found.

Here is a link that might be useful: Plan to save monarch butterflies backfires

My sister grows tropical milkweed. Her monarch's are healthy. I think it is because tropical milkweed does not survive out winters, therefore the monarch's migrate. I
I have the common milkweed and butterfly weed.

As usual, I've seen no Monarchs at all anywhere I've looked since the fall migration period. Today was finally warm and sunny after too much dreary winter cold, but so far, not even one sulfur butterfly flying around. It's been unusually cold this winter here. Nothing blooming.