Charles H. Spurgeon on Psalms 105:34

He spoke, and the locusts came, and caterpillars, and that without number. One word from the Captain and the armies leap forward. The expression is very striking, and sets forth the immediate result of the divine word. The caterpillar is called the licker, because it seems to lick up every green thing as in a moment. Perhaps the caterpillar here meant is still the locust in another form. That locusts swarm in countless armies is a fact of ordinary observation, and the case would be worse on this occasion. We have ourselves ridden for miles through armies of locusts, and we have seen with our own eyes how completely they devour every green thing. The description is not strained when we read, "And did eat up all the herbs in their land, and devoured the fruit of their ground." Nothing escapes these ravenous creatures, they even climb the trees to reach any remnant of foliage which may survive. Commissioned as these were by God, we may be sure they would do their work thoroughly, and leave behind them nothing but a desolate wilderness.