monarch caterpillars late in the season

monarch caterpillars late in the season

I've got 4 monarpillars in what appears to be 2nd instar, and today a 5th appeared that's wee wee teensy bebbeh 1st instar. These milkweed plants are not very old, and I read that in the last couple of stages the caterpillars can eat a leaf an hour o_O I don't have enough leaves for 5 'pillars to nom at that rate. Unless they'll eat the flowers and stems too? This is my first year with a host plant at all and I was really surprised to find the little guys, so I'm not sure what to do about the possible food shortage. I emailed the Texas Discovery Gardens where I bought the plants, because they sold me pregnant plantsthey're bound to have info, but I thought I'd also run my concerns out here and see what the more experienced might have to offer.
Bow chica bow-wow.

Bow chica bow-wow.

For what it’s worth…

For what it’s worth…

they’re coming up!

they’re coming up!

Thunder Bay Horticultural Society Annual Flower, Fruit and Vegetable Show

Thunder Bay Horticultural Society Annual Flower, Fruit and Vegetable Show

Critters and Weeds

Critters and Weeds

Zone-6  a question of leaf identification.

Zone-6 a question of leaf identification.