The Great Southern White (Ascia monuste) is a little smaller than the similar Florida White (Glutophrissa drusilla) and the Cuban White (Ganyra menciae).
The best diagnostic character is the bright blue tips of the antennae.

Top, Left & Middle: Oracabessa area, Jamaica, 20 January 2018
Right & Last: Hope Gardens, Kingston, Jamaica, 18 January 2018