Biting midges
Changes in climate suitability for biting midges are likely to create challenges for the beef and dairy industries.
Biting midges in NSW
Biting midges (Culicoides brevitarsis) are small parasitic midges that affect ruminating livestock. They are invasive to Australia but are permanently found in regions from the mid-north coast and north in NSW, continuing past the Queensland border. The midges' distribution relies on the presence of cattle and warm temperatures, and they can be spread over long distances by wind.
In Australia, biting midges are the main vector of arboviruses, such as Blue Tongue Virus (BTV) and Akabane viruses. This is due to their tolerance of tropical and subtropical climates, which increases their abundance in these regions compared with other Culicoides species. These viruses affect livestock production and yield and may cause animal fatalities. Stock movement restrictions may also be placed upon regions known to be infected by these viruses.
Biting midges are endemic to the coastal region of NSW. The map shows the endemic (yellow) distribution of midges across NSW. Casino, Coffs Harbour and Tocal represent the regions where biting midges are known to occur, and Lightning Ridge, Bourke, Wagga Wagga and Cowra are in areas where biting midges does not normally reside.
What is the NSW DPIRD Climate Vulnerability Assessment? ⏷
Climate change is altering the biosecurity risks for many agricultural commodities across NSW. Primary producers need evidence-based information about the changing climate, and the risks and opportunities it may bring.
The NSW DPIRD Climate Vulnerability Assessments are enhancing the resilience of our primary industries by providing information and data to help the sector better plan for, and respond to, climate change. They have assessed climate change impacts for extensive livestock, broadacre and irrigated cropping, marine fisheries, forestry, horticulture and viticulture, and important biosecurity risks associated with these industries to inform sound planning, risk management and adaptation decisions.
How we assessed climate suitability ⏷
Climate projections were sourced from Climate Change in Australia’s ‘Application Ready Data’. This dataset is comprised of projections from an ensemble of 8 global climate models, each presenting a plausible future climate. Low confidence in the projected changes due to differences between the models is noted in the text. Care should be taken when interpreting these results.
The Climate Vulnerability Assessment is intended to highlight potential industry- or regional-level changes. Intermediate and high emissions scenarios were used in the assessments (RCP4.5 and RCP8.5), but these are not the only future scenarios possible. The inclusion of climate variables important to the commodities production was based on published research, expert knowledge and data quality and availability.
Climate suitability was assessed on a monthly timescale, with the reported climate suitability representing the average for a given month over all years in the dataset. This reflects the pattern of life stages for buffalo fly and the need to determine which months are likely to pose the greatest risk to host commodities.
Learn more in the Climate Vulnerability Assessment Project Framework.
Climate impacts: expected challenges for primary industries
Changes in climate suitability are likely across all key life stages of biting midges by 2050, under both emission scenarios.
Changes to monthly climate suitability are likely to affect the biting midges in different ways:
- April to November – there are likely to be minimal to moderate increases in climate suitability in the endemic region (moderate to high confidence). The increases are likely to be greatest under the high emissions scenario.
- December to February – there are likely to be minimal to moderate decreases in climate suitability in the endemic region (low to high confidence). The decrease is likely to be greatest under the high emissions scenario.
- March – climate suitability in the endemic region is expected to remain similar to what has been historically experienced under both emissions scenarios (moderate to high confidence)
Under future climate scenarios, the effects of biting midges on the beef and dairy industries are likely to increase in NSW.
Increased climate suitability under a warmer climate will likely lead to increased numbers and expanded distribution of the midges, including outside of the historical endemic regions. This may increase the risk of transmission of arboviruses, leading to the need to decrease stock movement and increase quarantine practices. As a result, biting midges may cause significant economic impacts on the NSW livestock industry, especially as their occurrence and distribution increase.
Where can I find the climate suitability maps?
Maps of historical and future climate suitability for biosecurity risks were produced to demonstrate where in the state a biosecurity risk is likely to thrive or else be limited by future climatic conditions. The maps are not provided on these webpages but can be found in the Biting Midge Results Report (due to be released mid-2025). An overview is given in the Climate Vulnerability Assessment Summary Report (link below).
Biting Midge Factsheet
(PDF, 351.41 KB)
Summary Report
(PDF, 41425.92 KB)
