In the book The Prophetic Whisper, Richard Gazowsky shares the significance of a 40-day fast that the Lord gave him:
My wife and I had gone to Carmel, California for a time of extended prayer. On the third day, while we were praying at the beach, a swarm of flies ascended from the ocean surface as if orchestrated by an invisible conductor and swept like a blanket across the water and onto the beach. I ran over to the place where Sandy was praying to see if she was alright.
“Richard it is so strange,” she said. “While I was praying, I brought up the name of a pastor’s wife whom I knew had been tempted to commit adultery, intending to intercede for her. As soon as I mentioned her name, these flies rose up off the ocean.”
No sooner had she finished, then the Lord quickened my spirit and said, “I am going to show you a secret vulnerability in Satan’s kingdom.” His weakness is in the flies. Later that day, we went to the Carmel public library and looked up the word fly. I discovered the meaning of Beelzebub, and found one of the names of Satan is “Lord of the Flies.” Scientists have discovered that flies have a reproductive period from 4 hours to 40 days depending upon the species. When pest controllers go to eradicate flies in a certain area, they spray pesticides everyday for a 40-day period. If they destroy the reproductive cycles of presently existing flies, they can kill off a whole generation of future flies. I then saw what God was trying to show me. Satan can’t fight for long periods. If a Christian will pray consistently for a 40-day period, he will be able to conquer most satanic strongholds in his life.