Butterfly weed vs Common Milkweed?

[ButterflyLady_IL]

What's the scoop on having butterfly weed as the only larva food source available? Will the caterpillars grow as well as they do on common milkweed?
Has any research been done on the various milkweed species? Common, Smooth, Sandvine, butterfly weed and the growth of caterpillars?
I've been sharing our monarch activities with family members around the country, now have a sister-in-law with butterfly weed, and small caterpillars in Kansas. She's not sure if common milkweed grows around her area. But the adults found her small garden. She's now enjoying the wonder of watching the caterpillars grow.

[Pat]

I have several different species of milkweed / asclepias etc here and am starting more ... of the ones that I have enough of to feed to the caterpillars, it doesn't seem to make any difference at all to their appetites! My cats end up eating a mixed diet, since they get whatever I have the most of each morning, or whatever the latest wind or thunderstorm has broken off, so sometimes they get a couple of the huge milkweed leaves and sometimes they get whole branches of tropical asclepias.

[Keith Petrosky]

Are butterfly weed (orange flowers) and mexican milkweed (red and yellow flowers) different species or a hybrid of one another?

[Pat]

No, they are different species. Mexican milkweed is the "whorled" milkweed, asclepias fascicularia. I don't have any of that yet, it's a western plant. But I'm not sure about what you've got there because I don't think Mexican is red and yellow, it's the usual mauve-ish color for milkweed flowers, here's a picture:

Mexican whorled milkweed

The most common types of asclepias around here in the northeast are:

syriaca - tall, heavy mauve-colored flowers with a heady scent, very broad leaves, that's the "common" milkweed - perennial

incarnata - bushy perennial, with mauve flowers with not much scent, called "swamp" milkweed. One strain will put forth more branches and blooms if you snip off the deadheads; one strain blooms only once whether you trim it or not.

curassavica - shorter, gets about 3 feet tall, with clusters of red-and-yellow bicolor flowers and much more tender leaves than the others, also called "bloodflower" or "tropical" - not perennial this far north, you have to restart it from collected seeds each year.

tuberosa - also shorter, but perennial here; these are the ones with the orange flowers and the rather fuzzy leaves, also called the "butterfly milkweed". I have also seen a strain of this being sold that's supposed to be all-yellow, called Asclepias tuberosa 'Hello Yellow'.

The USDA Natural Resource Conservation Service has a nice layout of pictures in their plant gallery, you can see just the milkweeds here:

USDA NRCS Asclepias

[Megathymus ursus]

Butterfly weed (A. tuberosa) is less toxic than the wild milkweeds, and thus may produce "tastier" adults. Nutritionally it should be just as good. The best host for monarchs is A. curassavica.