Many mosquitoes, such as Culex
pipiens, lay their eggs on the surface of fresh or stagnant
water. The water may be in tin cans, barrels, horse troughs,
ornamental ponds, swimming pools, puddles, creeks, ditches,
catch basins or marshy areas. Mosquitoes prefer water sheltered
from the wind by grass and weeds.
Culex mosquitoes usually lay their eggs at night over a period
of time sticking them together to form a raft of from 100 to
300 eggs. A raft of eggs looks like a speck of soot floating
on the water and is about 1/4 inch long and 1/8 inch wide.
A female mosquito may lay a raft of eggs every third night
its life span.
Anopheles and many other mosquitoes lay their eggs singly
on the water surface. Aedes and Ochlerotatus mosquitoes lay
eggs singly, usually on damp soil. Aedes and Ochlerotatus
eggs are more resistant to drying out (some require complete
out before the eggs will hatch) and hatch only when flooded
with water (salt water high tides, irrigated pastures, treeholes
by rains, flooded stream bottoms). Anopheles, Culex and Mansonia
eggs are susceptible to long periods of drying out. Tiny
mosquito larvae (1st instar) emerge from the eggs within 24
- 48 hours
almost in unison.