Judges 6:1-6 (KJV)
1 And the children of Israel did evil in the sight of the LORD: and the LORD delivered them into the hand of Midian seven years.
2 And the hand of Midian prevailed against Israel: and because of the Midianites the children of Israel made them the dens which are in the mountains, and caves, and strong holds.
3 And so it was, when Israel had sown, that the Midianites came up, and the Amalekites, and the children of the east, even they came up against them;
4 And they encamped against them, and destroyed the increase of the earth, till thou come unto Gaza, and left no sustenance for Israel, neither sheep, nor ox, nor ass.
5 For they came up with their cattle and their tents, and they came as grasshoppers for multitude; for both they and their camels were without number: and they entered into the land to destroy it.
6 And Israel was greatly impoverished because of the Midianites; and the children of Israel cried unto the LORD.
The judgment that God brought upon Israel for their evil deeds was one of Israel’s own making. The instrument used by the Lord to chasten Israel was the Midianites. The reason that we are able to say that this judgment was of the Jews own making is the fact that the Midianites should not have existed at all in Gideon’s day. The Jews had been commanded by God four hundred years before to destroy the Midianites and they did not follow God's Command. (Numbers 31:1-18)
 The Holy Bible : King James Version. electronic ed. of the 1769 edition of the 1611 Authorized Version. Bellingham WA : Logos Research Systems, Inc., 1995