25 “And did eat up all the grass in their land, and devoured the fruit of the ground”. Even grass is fruit, as Scripture is wont to speak, which calls even the ripe grain grass; but it wished these two things to harmonize in number with the two which it had spoken of before, that is, the locust and the caterpillar. But the whole of this does belong to the variety of speech, which is a remedy for weariness, not to any difference of senses.
Source: The Enarrations, or Expositions, on the Psalms (New Advent)