Here's the way i cover Rev.9.
Rev 9:1-21
1 And the fifth angel sounded, and I saw a star fall from heaven unto the earth: and to him was given the key of the bottomless pit.
Since this "star" that falls from heaven was given a key, and it's to the bottomless pit, what is literal and what is symbolic? The star has to be symbolic being associated with an entity with a key, simple enough. The bottomless pit is a reference to Satan's abode. Jesus said in Luke 10:18 He saw Satan as lightning fall from heaven. The "star" represents Satan, and he fell from heaven in times of old when he first rebelled against God.
This fifth angel is the 5th trumpet - 1st woe period.
2 And he opened the bottomless pit; and there arose a smoke out of the pit, as the smoke of a great furnace; and the sun and the air were darkened by reason of the smoke of the pit.
Satan opens that pit, and smoke comes out of it. What's the smoke for? Mystery, deception, i.e., like smoke and mirrors, symbolically darkening the sun and the air. And notice the smoke is from that great furnace there in the pit, which is another symbolic reference for his abode. Notice it's not him that's being released at this point, but something else.
3 And there came out of the smoke locusts upon the earth: and unto them was given power, as the scorpions of the earth have power.
Do literal locusts come out of the pit of hell (hades sense), where Satan's abode is? No. These are symbolic locusts, not real locusts. God is using these locusts to represent Satan's workers released upon the earth in the last days, on the 5th Trumpet - 1st Woe timing. This is the first Woe upon the earth, so we should understand it as the first major attack, a spiritual attack. Because these locusts come up out of Satan's pit, some consider these locusts to represent a group of his angels coming to earth in the last days, as per Rev.12:7-9. I'll leave that for each one to ponder.
God is 'using' the idea of how real locusts in nature work upon the earth for their spiritual attack. Real locusts attack a crop in swarms, devouring everything in its path. These locusts have a direct association with God's prophecy given through His prophet Joel, for the end. In the Book of Joel, God reveals these locusts devour in 4 stages, what each previous stage misses, the next stage eats up, like completeness in devouring. But this devouring is spiritual though, as will be discovered later in this chapter. Famine is usually associated with real locusts devouring the crops. In Amos 8 God said the day will come when He will bring a famine in the land, but not one for lack of bread or water, but of hearing the Word of The LORD (i.e., understanding It). That idea should be kept in mind about these symbolic locusts.
God also attached the idea of scorpions with those symbolic locusts. So He's giving us more info on how else these locusts do their attack. Once again, consider how a real scorpion in nature works, and that's what He is pointing to. A real scorpion has no digestive system. It numbs its prey by stinging, and then vomits a fluid into the victim's mouth. The fluid acts as acid, turning the victim's insides, bones and all, to mush. Then the scorpion sucks it up leaving its victim like an empty shell. All that is being applied in the spiritual death sense about the locusts deceiving its victim.
4 And it was commanded them that they should not hurt the grass of the earth, neither any green thing, neither any tree; but only those men which have not the seal of God in their foreheads.
These locusts are commanded to not hurt any green thing on the earth. So they are not jet bombers, tanks, etc. So literal military war cannot be applied to this. They can ONLY hurt those men which do NOT have God's sealing. And those would be whom? The deceived, i.e., those under the famine, but not for bread and water, but for hearing the Word of The LORD. Thus Christ's elect are not subject to this stinging, period, for they are... sealed with God's seal, meaning they are not deceived by these locusts, nor under this spiritual famine ("...see thou hurt not the oil and the wine" - Rev.6:6).
5 And to them it was given that they should not kill them, but that they should be tormented five months: and their torment was as the torment of a scorpion, when he striketh a man.
The locusts cannot kill their victims, but only sting them for a period of five months. The scorpion sting is a spiritual sting to cause deception upon their victims. Should be getting the idea here that these represent false prophets for the end.
6 And in those days shall men seek death, and shall not find it; and shall desire to die, and death shall flee from them.
This is yet another pointer that these locusts are not coming to literally kill, but to work spiritually, the attack is to cause spiritual death to one's soul. Deception is what causes spiritual death, falling away from Christ to another instead.
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.
Now the locust shapes. Since these locusts so far are symbolic, this is going to help reveal what they literally represent. They were LIKE horses running to battle, and had as it were crowns LIKE gold on their heads, and they have the faces of men. They are men. And their crowns are LIKE real crowns of gold only, showing a type of fakeness. So Christ is giving us more symbols to consider their identity, while actually pointing to them being real men.
8 And they had hair as the hair of women, and their teeth were as the teeth of lions.
Their hair like the hair of women? A woman's hair is her crown according to Paul. In this sense it's about their smoothness, soft manner or approach. But their effect in that is as a lion attaching its prey. A lion that has clamped down on its prey will not let go until its prey is dead. These are all more symbols for how these locusts spiritually attack the deceived un-sealed.
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.
Since the kind of attack shown above is a spiritual attack, and not one of literal military attack, what KIND of 'breastplate of iron' would that represent? The Hebrew priests wore breastplates with 12 jewels. These are posing as priests, preachers, etc., but actually are false prophets, antichrists. And the battle they run to is spiritual.
10 And they had tails like unto scorpions, and there were stings in their tails: and their power was to hurt men five months.
Once again, their spiritual stinging was like how a scorpion works. And they were allowed to sting for five months. Our Lord Jesus is giving that as a repeat for emphasis, including that five months period.
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.
They have a leader over them, the angel of the bottomless pit. We know that cannot be some flesh man, but a heavenly being, the same one back at verse 1, Satan. The names Apollyon and Abaddon mean, 'the Destroyer'. Apollyomi is the Greek word for 'perish'. Satan and his angels only have already been judged and sentenced to perish in the future lake of fire. That's who their 'king' is here.
In Rev.11:1-13, that is still 6th trumpet - 2nd woe timing. At Rev.11:7 we're shown the beast that ascends from the bottomless pit will kill God's two witnesses. So that's showing this "king" (Satan) is released on earth for that period to do that. (understand, the 1st beast is a kingdom, and it does not ascend out of the bottomless pit. So the one of Rev.11:7 has to mean the "another beast" of Rev.13, the one speaking as a dragon, which is another title for Satan per Rev.12:9).
12 One woe is past; and, behold, there come two woes more hereafter.
Now comes the 6th Trumpet - 2nd Woe period, with one more Woe after that.
13 And the sixth angel sounded, and I heard a voice from the four horns of the golden altar which is before God,
14 Saying to the sixth angel which had the trumpet, Loose the four angels which are bound in the great river Euphrates.
The 6th angel sounds (6th trumpet), and the four angels bound at the river Euphrates are loosed. The Euphrates river was the literal northern border between Israel and the pagan nations. Their loosing represents an ordained working crossing that symbolic border with these locusts, since these locusts come out of the bottomless pit.
15 And the four angels were loosed, which were prepared for an hour, and a day, and a month, and a year, for to slay the third part of men.
These four angels have been prepared to do this loosing at a certain hour, day, month, and year; in other words, at a specific appointed time which God has ordained. And the locust's slaying doesn't involve literal flesh killing remember, but that stinging for five months mentioned above.
16 And the number of the army of the horsemen were two hundred thousand thousand: and I heard the number of them.
This is NOT some literal military army rushing to war on earth. The Armageddon event does not occur until Christ's coming which is later than these events. This is still about the locust army that stings like scorpions.
17 And thus I saw the horses in the vision, and them that sat on them, having breastplates of fire, and of jacinth, and brimstone: and the heads of the horses were as the heads of lions; and out of their mouths issued fire and smoke and brimstone.
Notice "jacinth" is mentioned about their breastplates. Jacinth was one of the precious jewels upon Aaron's priestly breatplate (Exo.28, as "ligure"). Notice where the fire and brimstone issues out of; i.e., their MOUTHS. Military armies don't destroy with their 'mouths', but with literal weapons. What does... come out of one's mouth? Words. That's what these attack with, so the slaying of a third part of men means what KIND of slaying? Spiritual slaying to cause deception.
Since our Lord Jesus and His Apostles forewarned us about a 'pseudo-Christ' coming in His place to be worshipped in Christ's place, that's the deception all this associates with for the end. Satan, as a "king" is who is involved in this, with his locusts preparing the field (world).
18 By these three was the third part of men killed, by the fire, and by the smoke, and by the brimstone, which issued out of their mouths.
Christ gives this point about what comes out of their 'mouths' doing the attacking for emphasis once again. So that killing is what KIND? Spiritual killing, to cause spiritual death in falling away (2 Thess.2:3-4).
19 For their power is in their mouth, and in their tails: for their tails were like unto serpents, and had heads, and with them they do hurt.
Now our Lord is giving us that pointer about what comes out of their 'mouths' yet another time! That's 3 times here for emphasis that this stinging is about false words by false prophets that serve Satan doing a spiritual killing to cause deception.
20 And the rest of the men which were not killed by these plagues yet repented not of the works of their hands, that they should not worship devils, and idols of gold, and silver, and brass, and stone, and of wood: which neither can see, nor hear, nor walk:
21 Neither repented they of their murders, nor of their sorceries, nor of their fornication, nor of their thefts.
(KJV)
Notice how these are 'contrasted' from those 1/3 in the previous verses. This latter group are clearly the wicked, idol worshippers, murderers, sorcerers, fornicators, thieves, etc., the truly wicked. So who are those mentioned previously that are the 1/3 that are stung? Since the stinging is spiritual to cause deception in falling away, the previous ones represent the deceived of God's people, spiritual harlots. They aren't these truly wicked, but they do become spiritual harlots for falling away to bow to the pseudo-Christ instead of waiting for our True Lord Jesus to return.