Yes, you can often switch them. Especially as they get bigger and hungrier.

Where in Michigan are you? I'm in Grand Rapids. I'm raising a batch of Monarchs, also, but would like to raise many more, or help others to succeed in helping them along.

Martha

I agree with Martha. My Monarch cats will switch to any other Milkweed without any complaints. Make sure and warn your friends about being careful not to get the milky sap on their fingers. That stuff can cause major major issues if someone wipes their eyes and gets it inside. I think that it's best if kids don't handle milkweed at all. JMHO.
Angie :)

Cats switch better in their later instars, in my experience (4th or 5th instars). The older the cat, the better the results. Ultimately, it's better to raise them on one variety if at all possible.
Good point about Milkweed's potential for irritation and eye injury.
Washing one's hands immediately after handling milkweed will prevent any problems caused by contact c the sap. Rubber gloves may also be used and carefully removed afterwards. But I think interested kids should be taught how to handle MW and cats properly. They can make great students and teachers too in our quest to save this fragile species.

Thanks everyone for all of the very helpful information. Docmom - I'm on the other side of the state, about halfway between Detroit and Ann Arbor. My son lives in downtown GR though (will be senior at GVSU and works out there too), so if I go visit anytime soon, I'll keep that in mind...especially if I find any more cats.