Adult mosquito trapping

The purpose of adult mosquito trapping is to collect samples for identification and documentation of species abundance and variation over a period of time or space. There are different ways to collect adult mosquitoes, and the method used will depend upon the aim of the mosquito monitoring activity. For routine monitoring purposes by local government, the most common method of adult mosquito trapping will be using an EVS/CO2 trap.

EVS/CO2 trap

The EVS/CO2 (carbon dioxide baited Encephalitis Virus Surveillance) trap is the most commonly used adult mosquito trap in WA. It uses both CO2, generally in the form of dry ice, and light as mosquito attractants. If dry ice is not available, the trap set-up may be fitted with a regulator and attached to a CO2 gas cylinder.  

The EVS/CO2 trap consists of: 

  • Dry ice tin: an insulated tin that holds the dry ice with holes in the bottom to allow CO2 to escape and a chain attached for hanging;
  • Verandah (optional): attaches to the dry ice tin to protect against adverse weather conditions; 
  • Battery operated motor unit: with a light to attract mosquitoes and a fan that draws mosquitoes into the catch bag and prevents escape; and
  • Catch bag: a plastic container and lid that is attached to the motor unit with a stocking net.

Selecting suitable trap sites

EVS/COtraps are designed to hang from sturdy, semi-horizontal surfaces (eg. tree branches, clothes hoists or similar). To improve the success of your catch and ensure mosquitoes remain in good condition for identification, ideal trap sites should be:
  • set amongst trees/foliage where mosquitoes are likely to harbour;
  • protected from rainfall, high winds and direct sunlight, as this helps prevent mosquito death and desiccation;
  • sheltered from sprinklers that may cause water damage to mosquitoes, making identification difficult;
  • free of large numbers of ants or other insects that may access the catch bag and eat the mosquitoes; 
  • accessible by foot, but not in plain view of the public who may tamper with the trap; and
  • set below head height (if not, it can be difficult to remove the trap and may also influence the collection of mosquito species).

Setting up an EVS/CO2 trap

To optimise your catch, it is preferable to set the trap before sunset and collect after sunrise as this is the period that most mosquito species are active. An EVS/COstandard operating procedure (613KB) has been developed to provide you with detailed information on how to operate an EVS/CO2 trap effectively. 

More information

  • Medical Entomology

Phone: (08) 9285 5500