What it is
Shellac is a resin secreted by the female lac bug, native to forests in India and Thailand. The resin is harvested by scraping it from tree bark; the process kills large numbers of bugs.
Why it matters
E904 is the glaze that gives jelly beans, chocolate-coated nuts, certain pills, and some apples their shine. It's also used in nail polish, hair lacquer, and wood finishing.
What to do
Not vegan. The Vegetarian Society does not consider shellac vegetarian-friendly either, due to the insect death involved in harvesting.