The plague of vermin or lice is not said to have stopped in the verses, (Ex 8:12-15). When, if at all, did it stop?
Credit Danno for pointing out this answer, by Menachem, that cites Rashi on Exodus 7:25, as well as unspecified midrashim: Moshe's age and the timeline of the exodus
The midrash can be found in Exodus Rabah 9:12 as an argument between R' Yehudah and R' Nehemiah. One says that warning of each plague lasted 24 days, and the plague itself lasted 7 days. The other says that the warning lasted 7 days and the plague itself lasted 24.
The Etz Yosef on that midrash provides more detailed information, including other sources, as to the consensus that events surrounding each plague lasted 1 month, with the exception of the plague of the firstborn.