Last week we reported soybean aphids had been found in MN, early enough in the season for it to be a bit of a surprise. What showed up in force the last week is no surprise at all – mosquitoes. The ubiquitous hum of summer has returned. These insects are not only annoying but transmit (vector) a number of diseases to mammals, including West Nile Virus (WNV). The Center for Disease Control still considers WNV to be an important insect vectored disease. The two mosquitoes apparently most likely to vector WNV are Culex pipiens and Culex restuans. Culex pipiens is one of, if not the, most common mosquito in urban and suburban areas in NE and the upper Midwest United States. In the Red River Valley, it is Culex tarsalis, an end of the summer nuisance, that is the likely culprit. The CDC has an excellent website with a lot of information about decreasing the chances of being exposed to the disease at:

http://www.cdc.gov/ncidod/dvbid/westnile/index.htm

They recommend the following steps:

Avoid getting bitten!

• Use an insect repellent, preferably containing DEET. Apply sparingly and use low-concentration products (15% - 30% DEET) on skin and lower concentrations for children and avoid applying repellent to children’s hands (to further decrease exposure to their eyes and mouths). Some people have had severe reactions when using DEET with sunblock and the CDC does not recommend using the two products at the same time. Avoid inhaling or contact with eyes and mouth. Pregnant and nursing women should minimize use as much as possible. Wash repellents off of skin after coming inside. As with insecticides, be sure to read the label and follow the instructions for any repellent you intend to use. Other concerns regarding the use of DEET and other insecticides and repellents are also addressed on links from the CDC cite:

http://www.cdc.gov/ncidod/dvbid/westnile/prevention_info.htm

• Spray light clothing with repellent containing either DEET or Permethrin (do not apply repellents containing Permethrin directly to your skin). Don’t apply DEET under clothing. Permethrin treated clothing will remain repellent even after repeated washings.
• Mosquitoes are most active from dusk to dawn, take extra precautions at night.
• Wear long sleeves and pants

Mosquito-proof your home

• Remove standing water from around your home; tires, birdbaths, rain barrels, etc all provide excellent breeding grounds for mosquitoes.
• Repair/replace torn or broken screens.

Help your community

• Report dead birds to local authorities. Details of how can be found on the web, for Minnesota at:

http://www.health.state.mn.us/divs/idepc/diseases/westnile/deadrept.html  

and for North Dakota at:
http://www.ndwnv.com/Testing&Reporting/Birdtestinginfo.htm  

• More info on handling dead bird carcasses can be found on the CDC site at:

http://www.cdc.gov/ncidod/dvbid/westnile/qa/wnv_birds.htm  

• Be aware of local mosquito control programs.
• Clean up potential breeding grounds. Any standing water represents potential breeding grounds for mosquitoes; clean up projects for vacant lots, parks, neighborhood wooded areas all can contribute to lowering local mosquito populations.

Ian MacRae
U of MN Extension Entomologist