agusanarse

To become infested with maggots or worms — used for rotting fruit, meat, or wood: la fruta se agusanó con el calor. A specific, slightly unpleasant verb for decay, common in contexts about spoiled food or wood-boring pests, not a general word for decay.

• Las manzanas se agusanaron antes de que las comiéramos. — The apples got maggoty before we ate them.
• La madera húmeda se agusana con facilidad. — Damp wood gets worm-infested easily.
• Tira esa carne, se agusanó por el calor. — Throw that meat out, it got maggots from the heat.

Using agusanarse as a general synonym for pudrirse (to rot) — agusanarse specifically means becoming infested with worms/maggots, a particular kind of spoilage, not decay in general.