This article appeared in the July 7, 2002 Sunday Express News Real Estate Section.

Rainfall Brings Mosquitoes Along With Green Grass - Nathan Riggs, Extension Agent - IPM (Bexar County Extension)

Extension Mosquito Factsheets
Mosquito Repellant Effectiveness Study from the New England Journal of Medicine

July 2002 began with a rainy onslaught and provided the South Texas area with much needed rainfall. While the benefits of the rainfall are numerous, let us not forget that the local insect fauna is enjoying the moisture as well.

One can't think of rain without thinking of the hoardes of blood thirsty mosquitoes that appear a few days after. Mosquitoes lay their eggs in watery tree holes, puddles, containers, tires and any other site that could hold water for 7 to 10 days. The eggs hatch into larvae (called wigglers) that feed on algae and other microscopic plants. After 2 to 3 days, the wigglers develop into a pupal stage that wiggles as well. In another 2 to 3 days, an adult mosquito emerges, ready to take on the world. Adult male mosquitoes feed on nectar from plants and do not feed on blood. The females feed on blood from animals, people and birds.

There are many species of mosquitoes that call South Texas home, but the most common is the Asian Tiger Mosquito (Aedes albopictus). This species is an aggressive biter and likes to harbor in ground cover, shrubbery and in flowerbeds.

With all of this in mind, there's still the hotbed question, "What can I do to control mosquitoes around my home?" Adult mosquitoes can fly up to 2 or 3 miles from their breeding sites, so controlling adults in the lawn may not last longer than a couple of days. However, treating the places they hide during the day will provide relief. Adult mosquitoes need high humidity and locations with ivy, groundcover, shrubbery or hedges fit the bill. There are a wide variety of non-mix products that can be attached to a water hose and sprayed on these locations. Overall, products containing permethrin, malathion or pyrethrins are the best bets for controlling adult mosquitoes.

Mosquitoes develop in standing water from tires, unused swimming pools, water gardens, flower pot saucers, pet dishes,tree holes, puddles, clogged rain gutters and other standing water sources. Refresh your pet's water dish daily with clean water. Be sure to dump out standing water where possible and use a larvicide such as Mosquito Dunks (image at left) to control wigglers in water gardens, ponds and other areas. They are non-toxic to fish, or animals that would live in or drink the water. Dunks will control wigglers for up to 30 days. Dunks are available at nurseries, feed stores, hardware stores and large retailers such as Home Depot or Lowe's. Mosquito repellants will provide a measure of relief against mosquito attacks while outdoors. In a recent study published by the New England Journal of Medicine, DEET-containing repellant Deep Woods Off! provided 301 minutes of continuous protection before wearing off while Sawyer Controlled Release , another DEET-containing product, provided 234 minutes of repellency. A poplular non-DEET repellant, Avon's Skin-So-Soft Plus, provided just 23 minutes of relief before bites occurred. Check out the repellant effectiveness study from the New England Journal of Medicine.

The most notable thing about this mosquito is its potential to transmit the West Nile Virus. It is not the only vector for this mild disease, but it's biting habits would place it at the top of the vector list. The West Nile Virus causes mild flu-like symptoms in people, but may cause death in horses and specific birds, including: crows, hawks and blue jays. West Nile Virus was positively identified in two dead bluejays from Houston during the middle of June 2002 and found in the Austin area from a dead blue jay during the first week of August, so it is only a matter of time before we see it in the San Antonio area. Horses can be vaccinated for this disease, so ask a local large-animal veterinarian for more information. For more information on West Nile Virus, go to the web at http://www.aphis.usda.gov/oa/wnv/index.html. If you find one of the birds freshly dead that are listed above, double bag it, freeze or refrigerate it and call the San Antonio health department office at 210/207-8853, the Texas Department of Health at 1-888-963-7111 or Dr. Catherine Tull at the Texas Department of Health Regional office in Uvalde at 830/278-7176.

Mosquitoes also carry the infective stage of the canine and feline heartworms (Dirofilaria immitis). Although not as much of a threat to cats as of yet, heartworms can significantly shorten the life of a dog to the point of death. Fortunately, there are products on the market such as Heartgard®, Interceptor®, or Revolution® that serve to protect your pet from this chronic parasite.

For those who purchased a "bug zapper" to control mosquitoes, think again. Mosquitoes are attracted to carbon dioxide in breath and not the ultraviolet light emitted by the zappers. If you dislike June Bugs, however, then the zapper will be your best friend because June Bugs are strongly attracted to ultraviolet lights..

There are new products on the market such as the Mosquito Magnet® and Coleman's Mosquito Deleto™. The theories behind them are proven, but check around with folks who have purchased one to get their evaluation of the product before spending your own money.

Don't let mosquitoes spoil your outdoor fun! Wear protective clothing with long sleeves and pants, keep a can of repellent handy and enjoy your time outdoors.

Try these useful factsheets on MOSQUITOES from Texas Cooperative Extension:

L-1744: Mosquito Control Around the Home (PDF file)
B-6119: Mosquitoes and the Diseases They Transmit (PDF file)