Butterflies can't fly if their body temperatures are below 82 degrees. That's probably why butterflies are found on all continents except Antarctica.
Butterflies do indeed taste with their feet. Since taste sensors are located in their toes (tarsi), when they land on a plant they can instantly tell whether it will provide a tasty meal or a good place to lay eggs. Their toes also have claws to help them cling, even upside down.
Though your mother may have warned you about this, butterflies will not instantly die if you touch them. However, too much touching rubs off the scales that create color on the wings and help the butterflies to fly, so your mother was right: don't pet the butterflies.
Instead of skin, caterpillars and butterflies have exoskeletons—they wear their bones on the outside. This armor protects the soft body inside and keeps the insect from drying out.
Because of the hard exoskeleton, growing caterpillars must molt several times before they enter the chrysalis. They secrete enzymes which dissolve the exoskeleton so they can reabsorb most of it. In a way, they're digesting their skins!
Butterflies and their caterpillars don't have lungs. Instead, they breathe through holes (spiracles) along their sides. Air flows naturally through the spiracles into internal tubes (tracheoles).
Caterpillars will only eat certain plants, and each species of butterfly has different requirements for caterpillar food. That's why gardeners who are trying to attract butterflies must plant certain host plants for mothers to lay eggs on.
When adult butterflies emerge from the chrysalis, they are unable to eat or fly. They must spend time inflating their wings and drying them, and they must coil and uncoil the proboscis so it forms a straw-like feeding tube.
If a butterfly lands on you it won't bite, but it may use its proboscis to take a sip of your sweat. Sweat contains salts that butterflies need in order to be healthy.
More than 750 different species of butterflies have been identified in North America. The largest butterfly in the world is Queen Alexandria's birdwing, which lives in Papua New Guinea. The smallest butterfly is the western pygmy blue, which lives in the western United States.
Answers to Kids' Questions About Butterflies from Scholastic.com [http://www2.scholastic.com/browse/article.jsp?id=4627]
Butterfly Basics from Michigan State University [http://4hgarden.msu.edu/butterflies/Butterfly%20Basics.pdf]
The Five Stages of Caterpillar Growth from JourneyNorth.org [http://learner.org/jnorth/tm/monarch/LarvaInstar.html]
The Butterfly Habitat portal page from the Smithsonian Institution [http://gardens.si.edu/butterfly/start.htm]
Get this bug off of me! from the University of Kentucky [http://www.uky.edu/Ag/Entomology/ythfacts/stories/hurtrnot.htm