Butterflies raised by unregulated commercial interests may spread diseases and parasites to wild populations, with devastating results. Often, butterflies are released great distances from their points of origin, resulting in inappropriate genetic mixing of different populations when the same species is locally present. When it is not, a non-native species is being introduced in the area of release. At best, this confuses studies of butterfly distribution and migration; at worst, it may result in deleterious changes to the local ecology.More at the link.
In addition, these releases create a commercial market for live butterflies (currently about $10/apiece), with the result that, for example, the Monarch overwintering sites in Mexico and on the California coast are now targets for poachers.
27 August 2010
Discouraging butterfly releases at weddings
The North American Butterfly Association discourages the release of butterflies at weddings.