Wetlands WA

Midges

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Midges (Chironomidae)

• Midges in Lakes Joondalup and Goolelall 2000

• Midges in Mary Carroll Park Lake

• A 2003 review of midge monitoring at Lake Joondalup

• Midges as a catalyst for lake rehabilitation

  • Copy of a paper presented at the Australian Environmental Health Conference in Perth 2001.

• 2005 Midge Research Results

  

           Adults                     Eggs                        Larvae

  Diagram of the midge lifecycle. Drawn by the late Dr Shirley Balla (used with permission). Click to see full size.

  If your are trying to identify Perth species, the best resource is the book - Davis J, Christidis F (1997) 'A Guide to Wetland Invertebrates of Southwestern Australia.' (Western Australian Museum: Perth)

• Wanneroo City Council Website 

  • Contains a good introduction to the problems and causes of nuisance midge plagues

  • Details of current monitoring in Lake Joondalup

• Midge Research Group

  • An overview of Western Australian research into nuisance midges 

• Taxonomic Key to Chironomidae

Dr Mark Lund

No one likes wetlands or lakes with poor water quality, but several insect species do. In particular some species of the Chironomidae (non-biting midges) thrive under these conditions. Non-biting midges are similar in size and shape to mosquitoes but do not bite. Adult midges lay eggs in wetlands, the eggs hatch to produce larvae (commonly called bloodworms) that live in or near the lake bed. They then form a pupae which swims to the water surface and out emerges the adult midge. The main purpose of the adult is to reproduce, which many do forming large spirally masses over the water surface. Adults generally do not live beyond a couple of weeks.

This all sounds very pleasant, but when several million adults emerge from a lake on a summer night and head towards the nearest lights you can have a problem. As most adults emerge during spring and summer the lights they are heading for are around your BBQ. Residents living near to wetlands can have their outdoor activities severely restricted during summer when huge clouds of midge descend on their houses. Despite the fact they are non-biting, sheer numbers make it hard to keep from swallowing them or getting them in your eyes.

Nuisance plagues of midges have been annoying residents surrounding Lake Joondalup for the last few years. The ultimate cause of the problem is human development around the lake, which has resulted in deteriorating water quality within the lake. The only short-term solution to the problem is to drop small pellets of a pesticide to the lake bed and kill the larvae before they emerge.

As an Environmental Manager this is a type of problem that you could easily face, on one hand you have a valuable ecosystem that has deteriorated and on the other residents who are suffering a severe decline in their quality of life. On the environmental side, you obviously would like to improve water quality within the lake, which would ultimately eliminate the midge problem but this may take anything from 5 to 50 years to be effective. On the human side you have the detrimental impact the midges have on quality of life, land prices and community. You need a short-term solution but the only one available is a pesticide that cannot be good for the lake.

This dilemma faced Dr Mark Lund of the Centre for Ecosystem Management at ECU in 1999 when he was asked to conduct research into the midge problem at Lake Joondalup. A survey of the lake revealed that midge larvae were concentrated into two ‘hotspot’ areas. These could be treated with pesticide while leaving much of the lake unaffected. The pesticide has been shown to have a negative impact on certain other organisms within the lake. Treating only some of the lake provided a refuge for these species while reducing significantly the problems for residents. This new approach is an improvement on normal treatments in Perth, which blanket the entire lake. However the use of pesticide is only a short-term solution and Dr Lund has been actively involved in both a public education campaign and in developing a longer term rehabilitation plan for Lake Joondalup. Good environmental management involves people and the environment and tries to find a ‘win win’ solution to an environmental problem. At Lake Joondalup, rehabilitation will eventually help reduce the midge problem, but in the process will benefit a wide range of environmental objectives. The residents will benefit through reduced midge plagues and a more natural ecosystem on their doorsteps.

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estern Australian wetlands, biomanipulation, restoration, rehabilitation, nutrient dynamics, Ord River, lake, lakes, rivers, river, nitrogen, nitrate, ammonia, phosphorus, constructed, artificial, stormwater, catchment, management, alum, aluminium sulphate, sulfate, carp, gambusia, mosquitofish,  Monger, Hyde Park, Joondalup, Collie, coal mines, voids, microbial, acidity, macroinvertebrates, zooplankton, midges, chironomidae, recycling, waste, Mary Caroll Park, history, ecosystem, function, ecological, aquatic, processes, ecological risk assessment, irrigation, research, postgraduate, student, projects, conceptual, model, pit lakes, mine lakes, AMD, ARD, acid mine drainage, acid rock drainage