The Northern Territory Health Department says the Top End needs to prepare for an “enormous wave” of mosquitoes.
The department says an unusually wet October and very high tides have created perfect breeding conditions for saltmarsh mosquitoes.
There was a big hatch of mosquitoes in the Top End in September, and the department says these insects have now all laid eggs.
Saltmarsh mosquitoes can carry the Barmah Forest and Ross River viruses and because of the hot and humid weather, can live up to two weeks longer than usual.
The department has sprayed insecticide around Darwin’s northern suburbs.
But it says Jabiru, Palmerston and Katherine will also be badly affected.
The department says mosquito numbers will not begin to drop until November.