after the end of school year on june 30, the summer holidays follow until september 1 when a new school year starts. since its introduction into the united states in 1868 or 1869, it has spread both west and south, now taking over most of the hardwood forests in the eastern united states and canada  over three hundred species of trees and shrubs are host to the gypsy moth. its weight was , which was too heavy for melting in a vacuum oven. the window on the central tower is  tall. 