Hisgalus 9:3-4

And out of the smoke came forth arbeh (locusts) to ha'aretz (the earth), and samchut (authority) was given to them like the samchut of the akrabei ha'aretz (scorpions of the earth). And it was told them that they should not harm the grass of ha'aretz (the earth) nor any greenery nor any etz (tree), except the Bnei Adam, all who do not have the chotam (seal) of HASHEM on their metsakhim (foreheads).