The Day of the Lord is near

Joel 1:1-20
Surely the joy of mankind is withered away, even the flocks of sheep are suffering.
For the grain offerings and drink offerings are withheld from the house of your God.
Alas for that day! For the day of the Lord is near; it will come like destruction from the Almighty.
The prophecy contains few clues to the date when it was written. We may guess at date - and guesses range from the 8th century BC to the 4th century BBC and later - but the book itself is timeless.
Joel is obviously familiar with themes which also occur in Isaiah, Amos and Ezekiel - particularly the 'Day of the Lord', when God will finally judge the world and his own people. What prompts the  prophet's message is a dire emergency, a plague of all-consuming locusts.
As the insect swarms hide the sun ad eat up the food supply, the prophet sees in them the darkness and suffering which will characterize that Day.
He calls the nation to repent, for God still loves his people and longs to rescue and restore them.
Why?
Even in the past 100 years Jerusalem has been stripped of all vegetation by a plague of locusts like the one Joel describes so vividly. The swarm of several million insects is carried into Palestine by the desert wind from Arabia.
The locusts grows rapidly from larva to winged adult, and at every stage its appetite is insatiable. It is worse than an invading army; when it moves on there is no green or growing thing left. There is nothing to offer to God, or so little that the people are using all they have to ward off starvation.
For Joel, the locust swarm is a sign, a warning of the terror of the Day of the Lord, God's approaching judgment day. He calls for a national day of prayer.
How?
Repent and pray to the Lord, for the Day of the Lord is coming soon!