Butterfly Host Plant and Metamorphosis
Baby butterflies. also know as caterpillars, eat plant leaves and tender new growth until they are sufficiently mature to form a chrysalis and metamorphize into an adult, flying butterfly.
Each butterfly uses a particular plant family to support their offspring. Adult female butterflies must lay their eggs on a specific plants, called host plants, so that when the young hatch they have the right food, the food with which they evolved, to eat.
Growing an abundance, as well a variety, of host plants will attract and support the largest possible population of butterfly babies to your garden. The female butterfly searches for the proper host plant on which to lay her eggs by testing each plant with sensors on her feet. Once located, she will lay her eggs on its tips where the tender new growth is found. Caterpillars prefer to feed on tender new growth, but when that becomes scarce they will eat the outer covering of the plant soaks, stems, and immature seed pods.
Planting one individual host plant will most likely attract a female butterfly to deposit her eggs, but it will soon be defoliated and will fail to provide enough food to satisfy the hungry, growing caterpillars. Therefore, planting host plants in a variety of locations throughout your landscape will ensure that a particular plant will not be eaten as quickly and will have time to bounce back faster with new growth. Also, if a host plant is eaten down to nothing, additional plants in alternate locations ensures there will be other areas in your garden where hungry caterpillars can be moved to if need be. Of, course, this depends upon the size of the plant and size of your available space. You certainly don't need more than one beach cherry tree, but four or five separate plantings of swamp milkweeds are doable even in a small space and provide quite a lot of monarch caterpillar food. Some plants will still be a little stressful for the new butterfly gardener. However, be patient and you will soon see that a balance between butterfly caterpillars and host plants, with occasional exceptions, will be achieved.
It is all well and good that butterfly gardeners rush to the store to purchase dill and parsley for their black swallowtail caterpillars, but butterflies really need natural plants in order for them to have a sustainable population. The hundreds of other butterfly species that aren't lucky enough to have easy to purchase larval food go hungry and their numbers decrease. A balanced butterfly garden should allow, and provide, for common species that aren't showy and popular like long tailed skippers, or Phaon crescent.
Caterpillars feed continuously for a few weeks during which time they grown considerably. Each time the caterpillar gets too large for its skin it completes a molt, which is when is sheds its old skin for a new one, larger one. During these periods, it stops eating and moves to an out of the way spot on the plant, most often at the base near the ground, and is very still for a day or so until the molt is complete. Each molt stage, or install, as it called, furthers the caterpillar's development and they typically experience four or five installs before entering their last developmental stage called pupation. The baby will soon become a flying butterfly!
Population is when the larval structure break down and adult structures such as wings, proboscis, and antennae, are formed. To prepare for this metamorphosis the caterpillar will move several feet away from the host plant and attach itself to a nearby shrub or structure. Some species will shed into a leaf litter to begin this stage. During pupation, the caterpillar will shed its skin for the last time, but instead of another skin, will develop a very hard chrysalis. After about two weeks an adult butterfly will emerge and trigger a repeat of this fascinating life cycle.