Traps area discussed in a position paper provided by the American Mosquito Control Association in their information section on mosquitoes. This organization, and others, provide useful information on mosquito biology, sampling and control. I have found a document produced by Health Canada particularly useful as an introduction to this field (Municipal Mosquito Control Guidelines). The Canada Communicable Disease Report (Vol. 31, 2005) also contains a free PDF guide to Personal Protective Measures to Prevent Arthropod Bites.

The Nzi trap was not developed to control mosquitoes, black flies, midges, etc. Nevertheless, it is capable of catching these smaller biting flies when baited with appropriate attractants and when equipped with netting of an appropriate mesh size. Below, I provide the few insights I have acquired in limited efforts to target these insects.

Mosquitoes

On the whole, mosquito catches are unpredictable relative to biting rates as species differences in behaviour towards traps are huge. The best example I have is from late June, 2005 near Great Slave Lake in the Northwest Territories. At extremely high densities of mosquitoes, I found considerable mosquito activity on and around traps, and yet surprisingly few mosquitoes entered traps. Below are some of my experiences at different locations where I have trapped on a more regular basis.

Since I started routine trapping at my home in Russell, Ontario, the highest catch I have obtained in an unbaited Nzi trap is 121 Aedes per day (mostly female A. vexans). Daily catches of a few to tens of mosquitoes are typical. By baiting a trap with carbon dioxide (dry ice) and octenol (Biosensory octenol lure), I have been able to catch 712 mosquitoes per day (I tried this bait on two nights only). Only some species of Aedes appear to be susceptible to trapping, with low catches of other taxa. Catches are particularly good for spring Aedes (e.g. A. punctor), which are active during the day.

The overnight catch on 18, July 2002

The mosquitoes were caught between 8 pm and 8 am in a Nzi trap baited with 5 kg dry ice and a Biosensory octenol lure at 23 °C, 80% Relative Humidity, and 14 km/h wind speed (means for the night). Most were the annoying man-biting species Aedes vexans. Codes for other components of the catch are: An - Anopheles punctipennis, BF - Simulium Black flies, Tabanus - Tabanus quinquevittatus.

Anopheles punctipennis (Intel^® Play^TM QX3^TM Computer Microscope)

This is an interesting mosquito present in small numbers later in the summer. Historically, malaria was found in this area; transmission is obviously still theoretically possible.

During trap development work in Africa, unbaited traps also caught few mosquitoes, but I mostly worked in areas with low populations. However, in Kenya, I occasionally baited traps with carbon dioxide when mosquitoes were present. This resulted in the capture of 50 -100 mosquitoes in a residential area of Nairobi, and many thousands of mosquitoes in a more natural area at Shompole (a swamp near Lake Natron). The Nairobi catch was mainly Culex quinquefasciatus, plus a few Anopheles funestus and Anopheles gambiae. The catch at Shompole was never identified.

I also tested carbon dioxide as an attractant at the AAFC dairy in 1999.