[cimmanom]

In the bilge of a ship, since they lay eggs in water?

[soperj]

Pretty sure mosquito eggs don't survive in salt water.

[samatman]

Bilge water isn't consistently salty.

A ship which unloaded in the St. Lawrence Seaway would fill the bilge tanks with fresh water.

[cimmanom]

Good point. I could still imagine puddles of fresh water from rain or from washing the decks languishing on in some corner of a ship.