Revelation 9:1  “…fifth angel sounded…a star fallen from heaven…To him was given the key to the bottomless pit”
Confronted again with the choice of literal or symbolic interpretation.  Even some of the commentators cannot decide.  Will go literal on some points and symbolic on others.  Best view seems to be just read the text and know the points and wait for God to fill in the blanks.  Then we can look at it as it’s happening or after the fact and say oh yes, I see what that meant.  As I’ve mentioned before, trust in God and listen to the Spirit.
Obviously an entity and not a physical star as it’s referred to as him.  Some question on whether it is satan or another high ranking angel.  Assuming it is evil as it is said to have fallen from heaven.  He’s given the key to the pit to open it and allow what is in there to come out.

2  “…smoke arose out of the pit…”
Pit could be Hell.  The smoke coming from the burning torment going on there.  The fact that other creatures come out is horrifying to imagine.

3  “…out of the smoke locusts came…”
Not locusts from the earth, but creatures which will behave or appear as locusts do.  Grouped together, moving in swarms.  Not sure if they are distinct creatures or demons in a particular form for this purpose.

3  “…to them was given power, as the scorpions of the earth have power”
Power to inflict pain and suffering.

4  “…only those men who do not have the seal of God on their foreheads”
Did no damage to the earth itself, grass or trees, but only men.  And not just any men, but only those who weren’t sealed by God, having the mark of God on their foreheads.  Side note:  had a conversation regarding tattoos recently.  Apparently God doesn’t have an issue with putting marks on His own.  Perhaps the issue is the meaning of the mark, not simply having it.

5-6  “…not…to kill them, but to torment them…torment was like the torment of a scorpion…men will seek death and will not find it”
Idea appears to be to punish mankind and not allow him to retreat by dying.  Normal scorpions, while having venom which can be fatal to humans, can’t dispense enough to kill full grown healthy adults.  But the neurotoxins can cause convulsions and shortness of breath.  In other words, make you severely ill to the point of death and cause great agony.  These creatures will have the same effect.  Men thus afflicted will want to die, but won’t be able to escape the torment that way.

7-10  Description of the creatures.  Again, hard to know if the description is physical or symbolic denoting the character or behavior of them.  And could be a bit of both.

10  “…Their power was to hurt men five months”
There was a time limit.  One commentary suggests it was the same time actual locusts would be a problem.  At any rate, it is something that has an end.

11  “…they had as king over them the angel of the bottomless pit…Abaddon…Apollyon”
Perdition or destruction.  The destroyer.  Sounds like another evil angel who is in charge of the Pit.  Probably not satan as he is roaming the earth.  Reminds me of the legion of demons who spoke to Jesus when He commanded them to come out of the man.  They asked that He not command them to go into the abyss.  They wanted no part of it.  Can only imagine the horror that will come out of it.

13  “…sixth angel sounded…

14  “…Release the four angels who are bound at the great river Euphrates”
Like the four angels at the corners of the earth.  Held in place to eventually allow destruction.  Apparently they are holding back the destruction awaiting the time for it to be unleashed.

16-19  “…the number of the army of the horsemen was two hundred million…”
Question as to whether this is an army of men or of demons or of men being driven by demons.  The descriptions of the armor and the way they caused destruction could be supernatural or a way of describing modern warfare.  One commentator suggests it may be a description of the war mentioned in Ezekiel 38-39, that of a Russian confederation moving against Israel.  If that is the case, it would place the Russian invasion after the Rapture.  A third of mankind is killed in the battle so the destruction is massive.

20-21  “…rest of mankind…did not repent…that they should not worship demons, and idols…they did not repent of their murders or their sorceries or their sexual immorality or their thefts”
Even after such devastation, the rest of the population still would not repent of their sin.  It is interesting to note that the punishment/destruction delivered isn’t really directly from God.  Instead He is merely releasing the hold on the evil that man has within himself.  If we take some of what is mentioned as literal, the natural disasters could be seen as direct punishments in order to get man’s attention, but most is a result of man’s own fallen nature.  Confronted with such evidence of his sin, man still refuses to repent.

I hope you enjoy reading and studying His word.  May it accomplish what He desires.  Please feel free to comment or post questions.  Thanks for reading!

Scripture taken from the New King James Version®. Copyright © 1982 by Thomas Nelson. Used by permission. All rights reserved.