For I am poor and needy, and my heart is wounded within me.
Read Chapter 109
Augustine of Hippo
22. "I go hence like a shadow that declineth" (ver. 22). By this he signified death itself. For as night comes of the shadow's declining, so death comes of mortal flesh. "And am driven away as the locusts." This I think would be more suitably understood of His members, that is, of His faithful disciples. That he might make it much plainer, he preferred writing "locusts" in the plural number: although many may be understood where the singular number is used, as in that passage, "He spake, and the locust came;" but it would have been more obscure. His disciples, then, were driven away, that is, were put to flight by persecutors, either the multitude of whom He wished to be signified by the word locusts, or their passing from one place to another.
Locusts. David was forced to wander about. Christ continually sought after the lost sheep, (Calmet) and was hurried to different tribunals. (Menochius)
St. Jerome applies this to the Jews, and St. Augustine to Christians under persecution. (Calmet)