Those who have studied the plagues brought upon Egypt through Moses have noted some obvious relationships between the different kinds of plagues. First the waters were turned to blood, driving the frogs onto dry land. Later lice were followed by flies, etc (Ex 6:20-8:24). Similarly, there is a relationship between the great dearth spoken of and the plague of serpents which followed. One author explained it this phenomenon:
"During my lengthy residence in Israel (1971-79), I had opportunity to visit the Musa Alami Farm near Jericho. The farm had been constructed after Israel’s 1948 War of Independence to settle displaced Palestinian refugees…Much of the farm was in disrepair during our visit because of the 1967 Six-Day War. Orange groves had died from lack of water, and most of the fields lay fallow. During the war, all but two of the pumps bringing underground water to the surface had been destroyed, making it impossible to maintain the farm at its previous level…Of particular interest to me was the effect on local wildlife. When crops were no longer being grown near the river, the mice moved westward to find grains in the few fields still under cultivation. They were, naturally, followed by serpents. From time to time, residents of the farm found vipers in and around their houses. This, they assured us, had never happened before the war.
“My thoughts turned to the story in Ether 9:30-3, where we read that the Jaredites were plagued by ‘poisonous serpents’ during a time of ‘great dearth’ when ’there was no rain upon the face of the earth.’…A similar tale is told of the Israelites during the period of the exodus from Egypt. Soon after arriving in the wilderness, where there was ’no bread, neither … water,‘ they encountered poisonous serpents ’and much people of Israel died.’ In this case, however, the serpents were not destroyed; instead, the Lord provided a miraculous means for the healing of those who had been bitten (Numbers 21:5-9; see also Deuteronomy 8:15; 2 Kings 18:4; John 3:14-5; 1 Corinthians 10:9; 1 Nephi 17:41; 2 Nephi 25:20).” (John A. Tvedtnes, FARMS: Journal of Book of Mormon Studies, vol. 6, no. 1, Fall-1997, “Drought & Serpents”)