Fancy dress balls grew so popular in the late 19th century that numerous books were published to suggest new and creative costume ideas. The most popular of these was probably Fancy Dresses Described: or, What to wear at fancy balls. by Adrian Holt. It went through numerous editions throughout the 1880s and 1890s (several of which are viewable online) and listed hundreds of costume ideas. This hornet costume from the 1884 edition is one of my favorites.