"And those in the front passed the word back to those behind. 'Scorpion. The baby has been stung." What is the significance of this incident in the novella?

Coyotito's encounter with the scorpion illustrates this possibility of danger that the family faces at all times and brings into focus the magnitude of their poverty, showing that their poverty places a tangible price on their existence that Kino may not be able to pay. The scorpion is a symbol of the furtive dangers that threaten Kino and his family, able to strike furtively at any moment. It is therefore analogous to the other enemies that will threaten Kino and Juana: the scorpion secretly enters the house and strikes at them indirectly, instead of presenting a direct and open challenge to them.