A very small wingless parasitic insect. Fleas are usually reddish brown and have short front and middle legs but long hind legs. The flea’s strong and spiny legs as well as its flat sides enable it to move with ease and rapidity between the hairs or feathers of its host. The short rearward-pointing hairs covering this insect’s oval-shaped body not only permit the flea to move forward readily but also make it more difficult for the victim to remove it. The flea’s small head is equipped with a beak that is used to pierce the skin of its victim, causing the blood to flow. Its leaping ability is phenomenal. Although less than 0.3 cm (1⁄8 in.) long, the flea that lives on humans can jump more than 30 cm (1 ft) horizontally and nearly 20 cm (8 in.) vertically. The Biblical variety of flea is probably that called Pulex irritans.
In Scripture the flea is mentioned only twice. When David was being pursued by King Saul, he questioned the king: “After whom are you chasing? . . . After a single flea?” By comparing himself to a flea, David emphasized his littleness in comparison with Saul, thus showing that it was hardly worth while for the king to chase after him. (1Sa 24:14) First Samuel 26:20 conveys a similar thought, but in the Greek Septuagint the words “a single flea” read “my soul.”