Revelation 9:15
"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."
Cross References (ranked by relevance)
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.
The first angel sounded, and there followed hail and fire mingled with blood, and they were cast upon the earth: and the third part of trees was burnt up, and all green grass was burnt up.
And the third part of the creatures which were in the sea, and had life, died; and the third part of the ships were destroyed.
And they had tails like unto scorpions, and there were stings in their tails: and their power was to hurt men five months.