Southern Saltmarsh Mosquito

Size: A medium-sized mosquito, with an adult body length of approximately 4-6mm.

Coloration: A brownish mosquito, distinguished by a mottling of brown, white, and golden-yellow scales on its thorax (back) and abdomen. The legs are dark with prominent pale bands, similar to other saltmarsh mosquitoes. A key difference from *Aedes vigilax* is that its proboscis is uniformly dark and lacks the distinct pale band in the middle.

Key Features: The most reliable features for identification are its southern distribution, its breeding in brackish wetlands, the brown and golden-scaled pattern on its thorax, and the lack of a pale band on its proboscis. Its ability to be active in cooler weather is also a key behavioural trait.

Body Structure: The standard mosquito body plan of head, thorax, and abdomen. The head features large compound eyes and the prominent proboscis. The thorax supports the legs and wings.

Legs: Six long, dark-brown legs with conspicuous pale bands, especially at the joints of the tarsal segments. This banding is a common feature of this group of mosquitoes.

Wings: Two clear wings with dark scales along the veins, typical of the family Culicidae.

Disease Transmission

• Ross River Virus: The most important vector of Ross River virus in temperate southern Australia, including Victoria and South Australia. Responsible for major seasonal outbreaks.
• Barmah Forest Virus: Also capable of transmitting Barmah Forest virus, though it is considered a less significant vector for this disease compared to others.
• Dog Heartworm (*Dirofilaria immitis*): Can act as a vector, transmitting the parasite to dogs.
• Myxomatosis: Historically involved in the transmission of myxomatosis among rabbit populations.
• The main human health risk is Ross River virus.

Allergens: The proteins in its saliva cause the typical allergic reaction of an itchy, red bump following a bite.

Risk Level: High

Vulnerable Populations

• Residents and visitors in coastal and wetland areas of southern Australia.
• People working or recreating outdoors (e.g., farmers, golfers, campers, gardeners).
• Unsuspecting tourists visiting popular coastal destinations like the Surf Coast or Mornington Peninsula in Victoria.
• Everyone in an affected area is vulnerable, as a single bite from an infected mosquito is all that is required for transmission.
• Children may have more pronounced skin reactions to bites.

Symptoms

• Of bite: An immediate sharp prick followed by an itchy, raised, red lump.
• Of Ross River virus: Debilitating and prolonged joint pain (arthritis), muscle aches, fatigue, fever, and a rash. Symptoms can persist for months.
• A diagnosis of Ross River virus requires a blood test.
• Seek medical advice if you develop flu-like symptoms and joint pain a week or two after being bitten extensively.
• Symptoms can significantly impact ability to work and perform daily activities.

Treatment Costs: Costs for professional barrier sprays are similar to other mosquitoes, around $300-$600. The major cost is borne by local and state governments for large-scale monitoring and larviciding programs.

Business Impact

Significant negative impact on hospitality venues with outdoor components. Mosquito swarms can make outdoor dining untenable.

Key Identifying Features

• A medium-sized, brownish mosquito with a mottled appearance of brown and golden scales on its thorax.
• Prominently banded legs.
• A uniformly dark proboscis (lacking the pale band of *A. vigilax*).
• Its southern Australian distribution and its ability to be active in cooler weather.
• Its aggressive, persistent, daytime biting habit.

Identification Tips

If you are in southern Australia (e.g., Victoria) and are being bitten by an aggressive, medium-sized mosquito with banded legs during the day, it is very likely *Aedes camptorhynchus*. The lack of a band on its beak is the key feature to distinguish it from its northern counterpart, *A. vigilax*, though this requires close inspection.

Similar Species

• Saltmarsh Mosquito (*Aedes vigilax*): Very similar in size and habit. The key difference is that *A. vigilax* has a distinct pale band on its proboscis, which *A. camptorhynchus* lacks. Their distributions overlap in NSW, but *A. camptorhynchus* is the dominant saltmarsh species in Victoria, SA, and Tasmania.
• Dengue Mosquito (*Aedes aegypti*): Breeds in freshwater containers, is smaller, and has a very different 'lyre' marking on its thorax. Not found in the same southern regions.
• Brown House Mosquito (*Culex quinquefasciatus*): A common pest, but is dull brown overall, lacks leg bands, and primarily bites at night.

Sanitation Measures

• Backyard sanitation to remove freshwater sources is not effective against this species but is still recommended to control other types of mosquitoes.
• The most relevant 'sanitation' is keeping your yard tidy by mowing lawns and trimming dense bushes to reduce the number of resting places for adult mosquitoes.
• Control of this species is primarily a community-wide and personal protection issue, not a backyard sanitation issue.
• Removing harborage sites can make your property less attractive to resting adults.
• There are no specific food or waste sanitation measures.

Exclusion Methods

• The most reliable way to prevent them from entering your home is with physical barriers.
• Ensure all windows and doors are covered with fine-mesh insect screens that are in good repair.
• Seal gaps around doors and windows to prevent entry.
• Use screened outdoor living areas to enjoy being outside without being bitten.
• Keep doors closed, especially during their peak activity times.

Landscaping Tips

• Manage vegetation on your property to reduce mosquito resting sites.
• Thin out dense garden beds and prune low-hanging branches to increase sunlight and air circulation.
• Keep grass short, as long, damp grass is an ideal resting spot.
• Avoid creating or maintaining habitats that hold brackish water, if applicable to your property (e.g., poorly managed agricultural drains).
• There are no plants that will effectively repel this determined pest.

Environmental Modification

• For homeowners, using powerful fans in outdoor entertainment areas can create enough wind to make it very difficult for mosquitoes to fly and land.
• On a larger scale, water management authorities may modify wetland hydrology to reduce breeding, but this is a complex and specialised task.
• Improving drainage in low-lying areas of a property could reduce potential breeding sites, although it primarily targets freshwater species.
• Reducing resting sites through vegetation management is the most effective modification a homeowner can make.

Chemical Control

Government-led larviciding of known breeding sites is the most effective control measure. A pest management professional can be engaged to apply a residual insecticide barrier spray to the vegetation and external surfaces of a property. This creates a treated zone that kills adult mosquitoes when they land to rest, providing significant relief for several weeks.

Biological Control

Government programs use Bti (Bacillus thuringiensis israelensis), a targeted biological larvicide, to control larvae in their breeding pools without harming other aquatic life.

Physical Control

Physical control is limited to personal protection, such as wearing appropriate clothing and ensuring houses are well-screened.

Integrated Approach

An Integrated Mosquito Management (IMM) approach is essential, combining public education, surveillance, biological and chemical larviciding, and targeted adulticiding when disease risk is high.

Treatment Effectiveness

Broad-scale larviciding can be highly effective. Professional barrier treatments can drastically reduce mosquito numbers on a treated property. Personal repellents are very effective when applied correctly.

Seasonal Activity

The primary season of activity is spring, summer, and autumn. However, its cold tolerance means it can be a nuisance pest for a much longer portion of the year than more tropical species, sometimes emerging after winter rains.

Daily Activity Pattern

A notoriously persistent and aggressive biter. It is most active at dusk and dawn but will readily bite throughout the day, especially on overcast days or in shaded locations. Its willingness to bite during cooler weather sets it apart.

Breeding Cycles

Generations per year: Multiple generations occur per year. In the temperate southern climate, breeding is most prolific from spring to autumn, but due to its cold tolerance, some breeding can occur even on warmer winter days if breeding sites are flooded.

Environmental Factors

The lifecycle is driven by the intermittent flooding of its breeding habitats. Rainfall is a particularly important trigger in many areas, in addition to tidal influences. Temperature modulates the speed of development.

Mosquito control should be conducted by licensed pest control professionals in accordance with local regulations. Check with your local council for any specific requirements regarding mosquito treatments and chemical applications.