What is the meaning of this fable?
Actually, the fable is about the grasshopper and the ant. "On the Grasshopper and the Cricket" is a poem by John Keats. The first line of that poem says it all: "The poetry of earth is never dead." Keats follows that by describing the grasshopper's song, which can be heard even when the weather is too hot for birds and other animals to sing. At night, the cricket takes up the song, even on the frostiest of nights.
If it is the fable of the grasshopper and the ant that you're asking about, just look at the moral at the end: "Idleness brings want", "To work today is to eat tomorrow", "Prepare for want before it comes".