Revelation 17

And there came one of the seven angels which had the seven vials, and talked with me, saying unto me, Come hither; I will shew unto thee the judgment of the great whore that sitteth upon many waters: With whom the kings of the earth have committed fornication, and the inhabitants of the earth have been made drunk with the wine of her fornication.

And there fell upon men a great hail out of heaven, every stone about the weight of a talent: and men blasphemed THE MOST HIGH because of the plague of the hail; for the plague thereof was exceeding great.

And I saw another sign in heaven, great and marvellous, seven angels having the seven last plagues; for in them is filled up the wrath of THE MOST HIGH.And I saw as it were a sea of glass mingled with fire: and them that had gotten the victory over the beast, and over his image, and over his mark, and over the number of his name, stand on the sea of glass, having the harps of THE MOST HIGH.And they sing the song of Moses the servant of THE MOST HIGH, and the song of the Lamb, saying, Great and marvelous are thy works, THE MOST HIGH; just and true are thy ways, thou King of saints.

They have the name of the Lamb and of his Father on their foreheads (7:3)They are with the Lamb on Mount Zion. They were redeemed from the earth. They did not defile themselves with women; they kept themselves pure.They were purchased from among mankind, and were offered as firstfruits to God and the Lamb No lie was found in their mouths; they are blameless.

And I saw one of his heads as it were wounded to death; and his deadly wound was healed: and all the world wondered after the beast

 And there appeared another wonder in heaven; and behold a great red dragon, having seven heads and ten horns, and seven crowns upon his heads.

And there was given me a reed like unto a rod: and the angel stood, saying, Rise, and measure the temple of God, and the altar, and them that worship therein.

And he had in his hand a little book open: and he set his right foot upon the sea, and his left foot on the earth,And cried with a loud voice, as when a lion roareth: and when he had cried, seven thunders uttered their voices

These locusts, sent from the bottomless pit, are commanded to harm only those without this divine seal. The seal signifies ownership by God and Christ, indicating believers belong to God and are thus protected from this specific plague. 

Woe, woe, woe, to the inhabiters of the earth by reason of the other voices of the trumpet of the three angels, which are yet to sound!