Exodus 10:14 - Ellicott's Commentary On The Whole Bible

The locusts went up over all the land of Egypt. — It is not, perhaps, certain that this is intended literally, since universal expressions are continually used by the sacred writers where something less than universality is meant. But, strengthened as the clause is by the succeeding one, we must suppose a very general visitation to be spoken of. Now Egypt extends, from north to south, a distance of above 500 miles, and the Delta has a width of 150 miles. No column of locusts having nearly such dimensions is recorded in history. Perhaps the visitation was confined to the Delta and the vicinity of Memphis. Even so, it would have covered an area of 7,000 square miles, or one nearly equal to that of Wales.