Revelation 9:7-11

7 And the shapes of the locusts were like unto horses prepared unto battle; and on their heads were as it were crowns like gold, and their faces were as the faces of men.

8 And they had hair as the hair of women, and their teeth were as the teeth of lions.

9 And they had breastplates, as it were breastplates of iron; and the sound of their wings was as the sound of chariots of many horses running to battle.

10 And they had tails like unto scorpions, and there were stings in their tails: and their power was to hurt men five months.

11 And they had a king over them, which is the angel of the bottomless pit, whose name in the Hebrew tongue is Abaddon, but in the Greek tongue hath his name Apollyon.

This passage gives the actual physical description of these creatures. They are not like anything we know. They are not helicopters or jets shooting missiles filled with chemical or biological weapons as some have speculated. These creatures come out of the smoke of the pit and the angel of the bottomless pit is ruling over them. This is not Satan because Satan at this point has not yet been cast out of heaven.

The king over these beings is named Abaddon. The name Abaddon actually means the  destroyer. These locusts are led by the destroying angel who is probably Satan's commander of the dimension called the underworld. These locusts are actual physical beings that ascend out of the same pit the angel in verse two opened with his key. The five months of this torment will be a literal hell on earth.