Butterflies feed on the nectar from flowers. Plant flowers full of nectar to attract them. Some top choices would be cosmos, butterfly bush, zinnia, joe-pye weed, pentas, lantana, purple coneflower, salvia, yarrow, firebush, blazing star, and mexican sunflowers.
Monarchs - butterfly weed, milkweed
Zebra longwings - passion vine
Tiger swallowtail - black cherry, tulip poplar, ash, willow
Black swallowtail - dill, fennel, parsley, Queen Anne's lace
The adult black swallowtail seems to know exactly how many eggs to lay on each host plant depending on the size of the plant. It takes three to five days for the eggs to hatch, where they chew their way out of the egg.
They go through growing stages which are called instars. They are very small in the first instar, and they are black with a white stripe around the middle section. In the second and third instars they are black with orange spikes and still have a white stripe around the middle section. Once they reach the fourth instar they are black with white stripes and yellow spots. When they molt into the fifth instar they will have green and black strips. The black stripes will have yellow spots.
They develop osmeterium, which is an orange spiked organ on the front of their heads, to fend off predators such as birds. When threatened the osmeterium will give off a bad odor.
When they are ready to pupate they will search for a protective spot. Pupa or chrysalis stage lasts nine to eleven days. For camouflage the color of chrysalides are green or brown depending on the foliage they are attached to.
Tips: Provide shallow drinking spots other than bird baths (birds eat butterflies), and flat stones in a sunny place so they can warm their wings.
Below are some photos I captured of the black swallowtail laying eggs and at each instar.
Happy butterfly gardening!