Up until about five years ago, you probably never heard of the West Nile Virus (WNV), let alone worried about it; but all that changed in 1999. That’s the year it was first detected in the Western Hemisphere. Since then, it has rapidly spread across the country to all 48 continental states, along with seven Canadian provinces, and throughout Mexico.
The spread of WNV begins with a bite from an infected mosquito. It’s the main route of transmission to humans. Mosquitoes become infected after they feed on infected birds. When that infected mosquito bites someone, the virus can be injected into the bloodstream, where it can multiply and cause illness.

With the heavy rains that fell in many parts of the country over the winter and spring, experts are predicting WNV activity to be high, due to the abundance of potential breeding grounds. Many of those breeding grounds are probably found on the properties in your care. While taking a proactive stance and addressing the problem before it takes hold is good business sense, the good will your vigilance creates can’t be measured in dollars.

The numbers speak for themselves. More than 15,000 people in the U.S. have tested positive for WNV infection; over 500 people have died. Many more have been infected, but experienced mild or no symptoms.

Statistically, the risk of contracting West Nile is low; less than 1% of those infected develop a serious illness. Those at highest risk for serious illness are people with lowered immune systems and the elderly. Yet, people of all ages can develop serious illness, so it is important that preventive measure be taken to minimize the risk of infection.

Those preventive measures start with a thorough inspection of the properties you service. To reduce the number of mosquitoes in outdoor areas, you need to reduce the number of places where they can lay their eggs and breed. That’s achieved by draining sources of standing water.

Experts recommend empting water from flower pots, pet food and water dishes, birdbaths, swimming pool covers, buckets, barrels, and cans at least once or twice a week. They also suggest removing any item that could collect water, along with checking for containers or trash in places that may be hard to see, such as under bushes or under the home.

Many of those procedures can be performed by you and your crew while on the property; or you can point out the potential hazards to your client so they can be addressed. Either way, you create good will by showing that it’s not just about the money, that you are concerned for their well being.

However, there are going to be situations where emptying water is not an option, especially if the property has water features such as fountains and ponds. In those situations, your client may want you and your company to take the preventive measures to stop mosquitoes before they can establish themselves. And those preventive measures will have to be maintained. The good will you’ve created can now be repaid by an add-on service that you can provide.

Since you can’t stop mosquitoes from coming into the backyard, the first line of defense is to prevent the area from becoming a breeding ground. Stagnant water provides an ideal environment for mosquitoes to lay their eggs. Because some species of mosquito have a limited flight range, your first step should be treating whatever water around the home can’t be drained.

“Any relatively shallow or moderately still body of water provides an excellent breeding ground for mosquitoes,” says Mark Krupka of Ecological Laboratories, Freeport, New York. “Whenever you’ve got what is referred to as a vector-born disease, the primary way of controlling it is to control the breeding ground.”

A mistake people often make is to assume that a water feature such as a fountain or a pond would not be a likely candidate for mosquitoes because the water is constantly circulating. And if the pond contains fish, the logic goes, there’s no way mosquitoes will survive because they will soon become fish food. In both instances, that is not always the case.

“Our industry is an inexact science,” says Jerry Goldberg of AquaMaster, Kiel, Wisconsin. “When given all of the criteria that we need for making the correct equipment suggestions to an end user, there is never a Utopia scenario. There’s always going to be an area that may not end up being totally aerated and have some degree of stagnancy.”

“Almost every pond is going to have some zones that are relatively still within the pond,” says Krupka. “In those areas, it would be possible for mosquitoes to lay their eggs. And some people say, ‘You know, I’ve got fish in my pond. The fish will eat the eggs.’ While there’s some truth to that, what we’ve found is that in addition to growing in areas of the pond that are still, mosquitoes breed in the slime that forms on the media in the skimmers and filters.”

Tales of pond owners opening up a filter, only to unleash a Pandora’s Box with a swarm of insects emerging, are not uncommon. That’s because most larvae tend to grow very well on the organic matter found in filter elements. The way the larvae end up in the filter is that the mosquitoes lay the eggs there in the first place, or the eggs eventually find their way into the filter due to the circulation of the water. Either way, if left unattended, it’s a situation that could have deadly consequences.

According to the Centers for Disease Control and Protection, about one in 150 people infected with WNV will develop severe illness. Symptoms can include high fever, muscle weakness, vision loss, numbness and paralysis. The symptoms may last several weeks; the neurological effects may be permanent

That’s why it’s important to take preventative measures, such as killing developing mosquitoes before they emerge as breeding, biting adults. Several products are on the market that use proven insect growth regulator technology, and can be easily applied in ponds and fountains where mosquitoes may breed, providing protection for several weeks.

The control these products offer is usually through chemical or biological means.
Deciding on which product to use depends upon your particular needs and concerns. They tend to come packaged in either granular or liquid form, although some products are designed to float on the water’s surface as they release their active ingredients.
Chemical controls tend to kill the larvae on contact; biologically controls take effect when they’re ingested.

While how they kill the insects may not seem important, you will want to make sure that whatever product you’re using, it doesn’t affect higher forms of organisms. Birds often frolic in water; dogs and cats drink from ponds. Just check the label before you add any substance to water that supports and can be accessed by living creatures.

Treating standing water, which is an ideal breeding ground, help control mosquitoes that carry West Nile Virus

“You want to use a product that’s EPA registered; that’s one of the important things to look for,” says Krupka. “There are some products out there that try to get around the EPA registration; they make claims and dance around the language.”

When a product is EPA registered, it means that all the lab and field efficacy data, as well as the toxicology profile, has been submitted to the EPA. The agency then reviews the data, and assigns the product a registration number.

Besides its toxicity to fish and other animals, other factors to consider include the affect the mosquito control has on the look and quality of the water, how often you must apply the product, how quickly it will achieve the desired affect, and the organic and inorganic residue it leaves behind.

A properly aerated pond will also work wonders in keeping down the mosquito population. An oxygen depleted pond will quickly develop algae, slowing down the aerobic nature of the water. Once that happens, the symptoms of poor water quality will rear their ugly head, including the infestation of mosquitoes and other insects.

“Any time you have water movement, you hope that you can have it oxygen-rich. That’s the key component,” says Goldberg. “You want to have high levels of dissolved oxygen in order to keep a water body healthy.” If the pond in your care doesn’t already have it, adding aeration will help achieve that goal.

To provide additional protection for an aerated pond, you can also treat the shallow regions along its edges with a broadcast granular larvacide, attacking the areas most susceptible to infestation.

“In the hot stagnant days of summer, the mosquito is looking for that serene, undisturbed warm area of the pond to lay its eggs,” says Goldberg. “That’s when you do a broadcast around the perimeter of the water body with a mosquito control product on a scheduled basis. That way you are proactive, killing the mosquito larvae before they become biting adults.”

Despite all your best efforts, however, some mosquitoes are going to find their way onto the property. Therefore, additional lines of defense are in everyone’s best interest. Some are obvious, but are worth repeating, and certainly passing on to your clients. Others are new approaches to an old problem.

Besides bug repellants that can be sprayed on clothes and skin, there are electric and propane-powered bug zappers that can be hung around the property. There’s also a new product called “Biter Fighter,” which uses non-toxic chemicals and water to create carbon dioxide that attracts the insects, and glue boards to trap them.

“What we have done is figure out a way generate carbon dioxide without electricity or propane,” says Dr. Ed Masters, of TOM LLC, Sikeston, Missouri. “You start the reaction by adding a spoonful of water to a one pound load of dry chemicals, and it will provide protection for a month.”

A newly formed, franchised company, Mosquito Squad, is taking a unique approach to minimizing mosquito activity. Using tubing and strategically placed nozzles, their technicians install a misting system that protects a yard by spraying the EPA-approved insecticide pyrethrum, two to four times each day for approximately 45 seconds.

The application of mosquito controls is also making its way into fertigation systems. FertiGator has a specially formulated supplement that is helpful in combating mosquitoes. Available separately, or included in their FertiGro Mojo line of fertilizers, FertiGro Repels is a blend of organic agents that help keep the unwanted pests away, yet is odorless and safe for children and pets.

“Gardeners have long known that garlic and other plant oil extracts are effective as mosquito repellents,” says Craig Lashmet, of FertiGator, St. Louis, Missouri. “However, their effectiveness was limited and inconsistent because they required frequent manual application and wide-area coverage. Using fertigation, we solve the application problem by consistently and automatically covering the entire landscape with all-natural pest repellents every time you water, creating an invisible barrier that prevents mosquitoes and other lawn pests from entering your property.”

Because experts are predicting a significant increase in the spread of WNV this year, contacting local vector control authorities as to the extent of the problem in your area is not a bad idea. Depending on where you live, the mosquito outbreak could last a while.

“In the warmer areas, it could be a longer season,” says Krupka. “Typically, the mosquito season is from June to October. But it could be year round in down in parts of Florida or Texas.”

To ignore potential problem spots on properties in your care is not only a health hazard to your clients, but may also open the door to litigation. If a neighbor without a pond contracts WNV, and can prove the pond in your care was a breeding ground where no preventive measures were taken, there’s a good chance a liability lawsuit will be filed against you and your client. But if you can show that there’s a program in place to control the insect population, you can mitigate, if not eliminate, liability.

Whether we like it or not, West Nile Virus appears to be here to stay. Since there are no specific treatments for WNV infection, nor is there a vaccine, preventative measures and knowledge are the only weapons you have to keep you and your clients safe.