Mosquito spraying starts ahead of seasonal peak

7 October 2011

Predicted surges in salt marsh mosquito numbers during this build-up period have prompted the Department of Health to ramp up controlled aerial spraying.

"A bacteria-based insecticide has been sprayed recently over 280 hectares of swamp in Leanyer, Holmes Jungle and Mickett's Creek this week," Director of Medical Entomology, Peter Whelan said.

"Other breeding spots around Darwin including Lee Point, Sandy Creek, Charles Darwin Park and Ludmilla Creek have been treated with slow release mosquito hormone pellets and briquettes," he said.

Salt marsh mosquitoes can carry the Barmah Forest and Ross River viruses, and according to Mr Whelan, September's high tide created the perfect breeding conditions for the carriers.

"Salt marsh mosquitoes lay eggs in the moist mud left when high tides have receded. After the eggs hatch the larvae take six days to reach adulthood and another three days to fly away from the breeding site," he said.

"This means we'll see a substantial pest problem from 8 to 17 October, with areas close to tidal swamps the worst affected."

Mosquitoes are expected to be most prevalent at the following locations, also listed on the Department of Health website:


  • Leanyer
  • Karama
  • Buffalo Creek
  • Holmes Jungle
  • Winnellie
  • Lee Point


  • Mitchell Creek
  • Brookings Creek
  • Hudson Creek
  • Elizabeth River
  • East Arm

Rural Area:

  • Noogoo Swamp
  • Millners Swamp
  • Howard Swamp
  • Knuckey's Lagoon
  • Robertson Barracks
  • Howard Springs Recreation area
  • Channel Island
  • Wickham Point area

Tidal Floodplains:

  • Daly River
  • Lower Adelaide River
  • Mary River
  • Lower Alligator Rivers
  • Lower Roper River

Inland Areas: 

  • Jabiru
  • Adelaide River Township
  • Katherine

The rest of the Northern Territory can expect elevated numbers of mosquitoes near coastal areas and within 10 kilometres of large brackish swamps and larger tidal creeks and rivers.

Areas outside the 5 kilometre limit of control from the edge of Leanyer and Karama are expected to produce an influx of salt marsh mosquitoes from the huge breeding areas around the mouth of Howard River and other areas around Shoal Bay.

Mr Whelan said October marks the start of the risk period for Ross River and Barmah Forest virus infection.

"The next big tide of 7.89 m in late October will cause another influx of salt marsh mosquitoes in the second and third week of November," he said.

Mr Whelan says people infected with Ross River or Barmah Forest virus may develop a wide range of symptoms, the most common of which are:
- painful or swollen joints (particularly in the hands, ankles and knees)
-  sore muscles
-  aching tendons
- skin rash
-  fatigue
-  fever
-  headache
-  swollen lymph nodes

"Symptoms generally last for a few weeks or months, though in some cases they can linger for up to 12 months," Mr Whelan said.

"Protection against bites is the best course of action as there is no vaccine to prevent Ross River or Barmah Forest virus."

People in the Top End experiencing mosquito pest problems are advised to:
- avoid locations near coastal swamps and mangrove areas
-  avoid outdoor exposure around dusk and at night near areas of dense vegetation and other areas of high mosquito activity
-  reduce outdoor activity in the evening and at night if mosquitoes are present
- use mosquito-proof accommodation and camping facilities at night
-  wear light coloured clothing with long sleeves, long trousers and socks between dusk and dawn in areas where mosquito bites are likely
-  use a protective repellent containing 20 per cent DEET or Picaridin as a supplement to protective clothing when outdoors at night in areas of mosquito activity
-  use mosquito coils, mosquito lanterns, and barrier sprays containing bifenthrin in patio and outdoor areas near houses
-  ensure children and animals are adequately protected against mosquito bites

Media Contact: Bridget Wild    89 99 2818 - 0401 116 203