David at the cave of Adullam thus addressed his persecutor Saul (1 Sam. 24:14): “After whom is the king of Israel come out? after whom dost thou pursue? after a dead dog, after a flea?” He thus speaks of himself as the poor, contemptible object of the monarch’s pursuit, a “worthy object truly for an expedition of the king of Israel with his picked troops!” This insect is in Eastern language the popular emblem of insignificance. In 1 Sam. 26:20 the LXX. read “come out to seek my life” instead of “to seek a flea.”
Flea
2 verses
1 Samuel
1 Samuel 24:14
After whom is the king of Israel come out? after whom dost thou pursue? after a dead dog, after a flea.
1 Samuel 26:20
Now therefore, let not my blood fall to the earth before the face of the LORD: for the king of Israel is come out to seek a flea, as when one doth hunt a partridge in the mountains.
From Easton's Bible Dictionary
Matthew George Easton, 1897