Rainfall of how much will raise water levels enough to cause mosquito eggs to hatch?

• A. 0.25 inch
• B. 1 inch
• C. 2 inches
• D. 4 inches

Answer: (B)

Mosquito eggs hatch when they are flooded with standing water. A moderate rainfall around one inch is typically enough to fill common breeding sites—such as plant saucers, tires, gutters, and low spots in yards—so the eggs that were laid above the water line become submerged and can start hatching within a day or two. If it’s only a small shower, the water may not persist long enough to allow hatch or to support larval development. Too much rain can create larger, deeper bodies of water or washing effects that aren’t as favorable for the eggs’ hatching process. So, about one inch of rain is the practical threshold that commonly triggers hatching in many mosquito habitats.