Container breeding mosquitoes are happy just about anywhere as long as they have a bit of water. This includes the Culex species that are the main vector for West Nile virus.
Recent increased amounts of rain have brought out the flood pool mosquitoes. These species lay their eggs in damp ground and patiently await inundation. When it comes, they can emerge in alarmingly large numbers. Heat and humidity speed up the development from egg to larva to pupa to adult. When many locations of the county are covered with standing water in grassy areas, it is a challenge to reach all the breeding sites in a timely manner to perform the appropriate control measures.
Then the weather changes, the nights cool, and with spreading frost the mosquitoes disappear. But where do they go and how is that they always return?
Flood pool species lay eggs that can withstand desiccation and cold temperatures. They overwinter in the egg stage. With snow melt, spring rains and warming temperatures, they hatch and begin the cycle anew. Culex and a few other species overwinter as adults. They hibernate in root cellars, bank barns, sewers, tunnels, animal burrows and sometimes our basements. It is not unusual to find a mosquito in the house during the winter months.
Female Culex enter hibernaculae bloodfed and mated. West Nile virus is transovarially transmitted to the offspring. If her last meal of the season was from an infected bird, the female emerges in the spring ready to lay infected eggs in the accumulated water around our homes. Those eggs hatch and develop into a WN infected mosquito. And another season begins…