Milkweed is the Monarch's host plant and is the only plant on which they will
lay their eggs. You will find milkweed growing in open sunny fields or along
the sides of country roads. Monarchs will check the plant before they lay their
eggs to make sure it is healthy and that there are not predator insects on it.
Then she will lay one single egg underneath a leaf.
If you find a milkweed plant with holes chewed in it, or caterpillar droppings on
the leaves, you are probably in luck. Look up and down the stem and underneath
each leaf and hopefully you will find a caterpillar.
Once you have found a caterpillar, you can either take it home in a jar or
on its host plant. If you take it in a jar, you will have to also take some
milkweed leaves and keep refreshing them every few days. If you take the plant,
you can keep it in water at home for about a week before you need another plant.
By keeping the plant in a jar of water, you can easily observe the caterpillar
as he climbs around and eats. He won't leave the plant, so you don't have to
worry about covering it.
If you decide to keep your caterpillar on the plant in a jar of water, be sure
to put newspaper underneath. As the caterpillar eats and grows he produces a
lot of waste and you probably don't want it landing on your kitchen counter.
If your caterpillar is in a jar, you will need to provide him with something
to climb on. When it is time for him to make his chrysalis he likes to climb
up to a place where he can hang down. If you are keeping him on the plant, he
will make his chrysalis underneath one of the leaves.
The chrysalis will start turning dark and see-through a day or two before the
butterfly emerges. This gives you plenty of warning to get it outside where it
can dry its wings in the sun and fly away.