(Back to school time with an Edwardian schoolboy costume, which was probably an easy fancy dress choice for a young boy who could simply use his own school clothes or uniform. Yes, despite the long hair, that's a boy.)
Straw hat; blue and white or red and white striped blouse; white or blue flannel trousers with stockings to match; laced shoes.
Source:
Masquerades, Tableaux and Drills. New York: The Butterick Publishing Company, 1906.