Answer: a break in
Step-by-step explanation:
The kids led by Jack kill a pig that was peacefully nursing its piglets. The scene is a metaphor for a violent break-in, an invasion upon an otherwise tranquil and blissful life in nature. The boys´ attack is gruesome, they show no mercy and chase the pig through the unless beautiful setting, full of flowers and butterflies, in a poetic display of human depravity.