This is a myth! Butterflies that can be purchased for weddings are raised by IBBA
member breeders who must follow strict standards for raising and shipping the butterflies. The process is completely safe and doesn't cause harm to the butterflies. In addition, releasing butterflies isn't harmful to the ecosystem because they are only shipped to native locations, adhering to USDA regulations on the transit of butterflies. For example, Painted Lady, Gulf, Red Admirals, and Monarch butterflies can be safely released in almost every state. Experienced breeders raise the butterflies in captivity -- they are not taken from the wild. There is no environmental threat in releasing butterflies in this manner.
Shipping doesn't pose a problem because the butterflies are placed inside a cardstock box to keep them safe, and fed beforehand. They are enclosed by soft padding and placed in an insulated cooler with a freeze pack. The lack of light and cool temperature keep the butterflies inactive during overnight shipping.