Which species lays eggs in clusters or rafts (50-500 eggs)?

• A. Culex quinquefasciatus
• B. Aedes albopictus
• C. Psorophora ferox
• D. Ochlerotatus triseriatus

Answer: (A)

The main clue here is the egg-laying pattern. Culex quinquefasciatus lays eggs in floating rafts on the water surface, with each raft containing about 50 to 500 eggs. This raft formation is a distinctive trait of many Culex species and helps differentiate them from others that lay eggs in different ways.

Other mosquitoes in the list tend to lay eggs differently: Aedes albopictus and Ochlerotatus triseriatus typically deposit eggs on the inner walls of containers or in small clusters that aren’t floating as a single raft on the water surface. Psorophora ferox, a floodwater species, lays eggs in moist soil or vegetation and them hatch after flooding, not as rafts on the water. So the large, floating raft of eggs (50–500) points to Culex quinquefasciatus.