To: Salisbury Post
From: Darrell Blackwelder
Re: Information on West Nile Virus, etc

    We are likely to see sharp increases in Asian tiger mosquitoes in the coming weeks as a result of our recent rainfall. While the rains were not enough to put a dent in our drought, they were more than adequate to provide breeding grounds for the mosquitoes. In addition, because of water restrictions, residents are collecting rainwater to water plants. Backyard inspections conducted this week across the state found buckets filled with rainwater at a fairly large number of residences. The potential mosquito problems resulting from this practice are obvious.
    Another very significant, but often overlooked production site are the receptacles that are placed under potted plants to collect water. Over 50% of the plant pot receptacles contained mosquito larvae or pupae. While this may conflict with people's need to water plants, it is preferable that water not be allowed to remain in the dishes beneath plants. Any standing water source is a potential mosquito breeding ground and needs to be removed wherever possible. Ordinary window screening placed over water collecting buckets and barrels will help exclude mosquitoes. Some of the large barrels being sold for collecting rainwater are equipped with such screening.
    Another approach is to eliminate mosquitoes in such breeding sites is to use the "Mosquito Dunks", the donut-like tablets that contain Bt (Bacillus thuringiensis israelensis) that kills mosquitoes, fungus gnats and a few other fly species. There is also a granular form of the product called 'Mosquito Bits'. As with any pesticide, the instructions for using the products are on their labels. These products are not intended for use in bowls or buckets used a drinking bowls for pets.
    Many are asking about what they can spray for mosquitoes. There are electric and gasoline-powered fogging machines available in retail stores, but as with any do-it-yourself pest control, results will be far less than expected. Fogging your yard does help reduce the number of adult mosquitoes, but it has little (if any) impact on the source of the infestation, i.e., the breeding areas, particularly in areas where Asian tiger mosquitoes are prevalent. We cannot emphasize enough the need for caution and care if someone attempts to use such machines. Read and follow instructions before applying any pesticide.
    Spraying lawns and shrubs will also kill resting mosquitoes, but again it is not likely to have a tremendous impact overall. Mosquitoes don't understand the concept of property lines and they're just as inclined to fly anywhere (including from untreated areas) in search of a meal. Mosquito control, chemical or non-chemical, has to be a community effort. There is likely to be another surge in interest about using the mosquito trapping devices found in the retail stores or sold over the Internet. As we have stated previously, the devices will attract many (but not all) species of mosquitoes. There is a lack of scientifically based data to show that these devices will actually have any impact in reducing mosquito populations and, more far more importantly, provide the type of protection that the public expects. We still do not recommend these devices as a primary means of preventing mosquito bites or the potential of mosquito-borne diseases. 

    Health officials and entomologists are recommending the careful use of insect repellents, limiting their use on small children as the best method for controlling mosquitoes .Information about mosquitoes, West Nile virus and other mosquito borne diseases, with links to important information from NCDENR Public Health Management can be found on our website at: http://insects.ncsu.edu/westnile.htm Information about insect repellents is found at: http://insects.ncsu.edu/Urban/repel.htm

Darrell Blackwelder is an agricultural agent in charge of horticulture with the North Carolina Cooperative Extension Service in Rowan County. For archived garden columns or other information, visit the Rowan County Master Gardener web site at www.rowanmastergardener.com or e mail Darrell_blackwelder@ncsu.edu
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