I heard some times later Instars will eat watermelon and/or pumpkin.

LOL... the more you plant/the more you'll get/the more you'll need. I was in the same boat as you, and luckily found a big patch of milkweed growing on the greenbelt near the house I was living in at the time. When I ran out of mine, I got cuttings from that patch. I moved in late summer, took my caterpillars with me, and had to go back to that patch to see them through :)

Try contacting your local parks & recreation office, or agricultural office, or highway dept. to see if they know of any areas where the milkweed grows wild. Of course then you'll have the problem of not just getting cuttings for your current babies... you'll start searching the wild patch for eggs and caterpillars, and take them home.... it's a vicious yet lovely cycle.

Thanks, can you get pumpkin this time of year?

Thats a good idea Weed! But I definitely won't take more eggs and caterpillars home! Well, maybe.....

I'm sure ya can get pumpkin. I don't see why not.

There is a lady in San Francisco that has milkweed, but needs Monarchs.

Here is a link that might be useful: Lady who has milkweed in CA