We hear the 5th and 6th trumpet and the first of the three woes (8:13). Notice that the destruction outlined in these chapters (seals and trumpets) correspond to the ten plagues visited upon Egypt in Moses' time, only they have been compressed to number only seven. It was believed in the ancient world that evil beings were chained to rivers and in "bottomless" pits. Locusts (3) were identified in biblical times as a sign of judgement from God. These locusts are a bit unusual (7) the the locusts look like horses equipped for battle, human faces long hair (like women's) armored (scales like breastplates) it sounds like many chariots and they have stingers. It is possible that this description is intended to mean the Parthians: the Parthians (9:8) had become famous for their rearward archery: they had retreated up hills mounted on horseback, and when unwary Roman legions had followed them, the Parthians had released a backward hail of arrows, wiping out several legions before the Romans learned not to follow them up hills. The reference to the Parthians seems remote to the modern reader. In Roman times the Parthians were Rome's most feared enemy and were never conquered. The river Euphrates was the eastern boundary of the Roman empire (to the east was the heart of Parthian territory). Many parts of the Roman Empire feared a Parthian invasion and, according to some records, the Jews in the Jewish revolt of AD 67-71 expected the Parthians to show up in support of their battles (which they never did).
Even with all of the destruction and hardship people did not repent of their wickedness. Life is difficult. Hardship and struggle drive many of us to seek our purpose and our creator. That same hardship and struggle drives others to even more evil behavior. What is it that drives one person to rail against the darkness and curse the one who made us and another to search for the light and grace contained therein?