<human>:  When did the locust plague occur?
<bot>: The locust plague occurred in the year 599 BC. It was a devastating event that caused widespread famine and death. The plague was caused by a swarm of locusts that descended on the land of Egypt. The locusts ate all the crops and left the land barren. The locusts were so numerous that they darkened the sky and darkened the sun. The plague lasted for three years and killed over half of the population of Egypt.