West Nile Virus Update: More Spraying in 2015 compared to 2014

City of Dallas Code Compliance crews have had a busy summer battling the city’s mosquito population and Code Compliance Services Officer Jonathan Thompson has been an active participant in that effort.

Thompson and the Code Compliance teams trap and test mosquitoes for West Nile Virus, then spray the areas around the city that have positive results. “More positives equals more spraying. We do have more positives than last year,” Thompson said. That means more Code Compliance trucks are on Dallas roads this year.

In 2014, the City of Dallas had 48 spray dates. Compare that to this year. Because of the increase in positive tests, Dallas crews already have 59 spray dates under their belt and still have a month left in mosquito season. Although the number of West Nile Virus positive mosquitoes has increased, the number of human cases remains fairly consistent with previous years.

“Luckily we have had a lot of citizen involvement putting in service requests for us to go check it out,” Thompson says. That ‘s one way Thompson finds houses that are breeding grounds for mosquitoes.

During the summer, Thompson drives to areas of concern, some reported through the city’s 3-1-1 reporting system. He steps out of his mosquito control truck and walks into the backyard of an abandoned house in North Dallas. “We’re out here because it’s most likely breeding, and if it is, we will take the necessary precautions.”

Mosquitoes can breed in very small amounts of water, so, with an abandoned pool, this location was sending off serious red flags. “Oh yeah, you can definitely see them in there,” Thompson says as he looks over the edge of the backyard pool with several inches of dirty, brown water standing in it. He plunges a cup into the water and pulls it out: “you can see the two different stages, the long skinny ones are larva and the ones that are more round and tumble a lot are pupa.

“It’s pretty obvious that it’s breeding so now we have to determine what to do with it. Because it’s a pool so it’s a contained environment, I’m not worried about what larvacides I use because it’s not going to affect the surrounding environment,” Thompson says. It’s a two-step process. Slow dissolving pellets will prevent breeding for several months, and a simple mineral oil will take care the larva already living in the standing water. “They breathe at the surface of the water, so we put a small sheen of mineral oil on the top and they can’t breathe.”

Citizens can report any areas of concern to the city’s non-emergency line: 3-1-1. “The best thing is to get rid of the water, if you can’t get rid of the water, treat it, and if you can’t treat it, then call us and we can at least help figure out what to do,” Thompson says.

Remember the Four Ds:

DRAIN standing water in your yard and neighborhood. Standing water can be found in swimming pools that are not kept clean, ponds, pet watering dishes, birdbaths, potted plants, old tires, empty containers, toys and clogged rain gutters.

DUSK/DAWN are the times of day you should stay indoors when mosquitoes are most active.

DRESS in long-sleeved shirts and wear pants when you are outside. Spray thin clothing with insect repellent.

DEET (N, N-diethyl-m-toluamide) is an ingredient to look for in your insect repellent (or use an organic alternative such as orange spray, eucalyptus or citronella).