Midges are often called sandflies but not every sandfly is a midge. Sandfly is a common name for a number of types of small biting insects.
Until recently midges have been a minor nuisance in Brisbane. However their presence and nuisance has been increasing since the arrival of a more serious pest species C. ornatus in the western suburbs.
Effect of midges
Midge bites can:
- cause severe itching that can persist over time
- result in open sores caused by prolonged scratching - in extreme cases, the sores can become infected and so itchy that they disturb sleep
Consult your doctor for advice on treating sores and reactions from the biting midge.
According to Queensland Health midges do not transmit disease in humans in Australia.
Personal and household protection
Some steps may provide personal and local protection from midges.
Wear light coloured clothing (preferably long pants and long sleeves) when outdoors, particularly in the early morning, late afternoon and into the evening.
Use insect repellents as directed. Consult your family doctor on the suitability of insect repellents for short and long term use by members of your family.
There are two ingredients most commonly used. Check the list of ingredients on the can or bottle:
- diethyl toluamide (DEET). The concentration of DEET will vary and it will be higher in the ‘tropical’ strength formulations. When the biting midge numbers are intense, higher concentrations of DEET would be more effective - somewhere around 15-20%
- picaridin is the alternative active ingredient in some insect repellents. It has only been in use in recent years but is developing a good reputation
- use ceiling and pedestal fans as a deterrent - midges don’t like air currents
- window screens can be sprayed with an aerosol residual spray to reduce numbers of midges coming through
- 240 volt plug-in pads may help
- mosquito coils work reasonably well
- small lanterns that have a tea candle burning under an impregnated pad are also available at supermarkets. They have the same active ingredient as mosquito coils but at 100 times the concentration
- there is a product similar to the small lantern that uses a mini gas cylinder to heat the pad
- these products are meant for outdoor use only
Barrier or harbourage treatment involves applying residual pesticide in the yard around your house. This treatment may reduce midge numbers for up to six weeks though not totally eliminate the pest. The pesticide is applied to shrubs, foliage, fences, house walls and screens.
Licensed pest controllers may use a product to do this. Its key active ingredient is bifenthrin, a synthetic pyrethrin.
There are also products available on the supermarket shelf with bifenthrin, in ready to use one, two or three litre packs with a hand trigger. If choosing to use these products, you must take care to follow the manufacturer’s instructions.
This chemical treatment is indiscriminate and will kill most other insects over the six-week period that it is active. It should not be applied to plants that are in flower and attracting other insects.
What Council is doing
Council is coordinating research to learn more about this pest including:
- what caused the serious pest species C. ornatus to move to Brisbane
- if it is here to stay
- if it will continue to spread
- if there are more effective ways to protect households, work places and recreation areas without harming the environment
- if there is an environmentally safe way to prevent it from breeding
Brisbane City Council has been controlling mosquito larvae for many years using environmentally safe chemicals, however the midge can not be controlled over broad areas because:
- there are no chemicals available or registered in Australia to control midge larvae
- the larvae live in mud in fragile ecosystems. Unacceptably high concentrations of chemicals are needed to penetrate the mud and control them