Mosquito FAQs

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The Texas Department of State Health Services recommends that screens on doors and windows be in good condition and that you use personal protection. Personal protection includes dressing to minimize exposed skin, wearing insect repellent and avoiding the outdoors during the hours of dawn and dusk (6 a.m. to 9 a.m. or 7 p.m. to 10 p.m.) which is when mosquitoes that have been identified as possibly carrying the disease are out. It also includes identifying areas of your property that may have stagnant water. 

The CDC states that precautions should be taken with insect repellent for children of certain ages. Parents with questions or concerns about repellents should consult their family physician. Most doctors can direct you to other resources that explain alternatives to the active ingredients found in most repellents. 


  • Positive West Nile Mosquito found after trapping.
  • When very heavy populations of mosquitoes are trapped.
  • A human case of West Nile Virus has been isolated. 

Tuesdays and Thursdays between 9:30 p.m. and 1:00 a.m.

Heavy to moderate rain and/or wind conditions above 10mph.

The approximate duration is 1 hour after it is dispensed.

The chemical used in spraying should have little effect on individuals asthma; however, individuals should take steps to minimize exposure to any pesticide.

As a precaution, pets should be brought inside.

Swimming pools -- no. Fish ponds -- yes.

No, however as a precaution outdoor toys can be washed with soap and water to minimize contact. 

Yes; however, only at the request of the school district.

The City treats stagnant water with a larvicide. This is an integral part of the approach recommended by the CDC in minimizing the number of mosquitoes in our area. The City also conducts a mosquito surveillance program by trapping and testing mosquitoes for West Nile Virus. Mosquitoes are a direct indicator of human illness risk when it comes to West Nile Virus.

It is recommended you stay indoors during application, bring pets indoors and refresh outdoor animal water containers the next morning.  Notify the City if you have an outdoor pond or water feature that contains aquatic wildlife. 

At this time, the Texas Department of State Health Services recommends residents not allow water to stagnate. Citizens can help by removing sources of stagnant water on their property. Areas to check include french drains, gutters, old tires, flowerpots, trash containers, swimming pools, bird baths and pet bowls. Citizens may actively treat areas of stagnant water on their property, not including creeks and other protected waterways.  Mosquito larvicidal treatments can be purchased at feed stores and home improvement stores.

As recommended by the Texas Department of State Health Services the City does not ship birds for testing. Birds are dead end hosts. Efforts are concentrated on mosquito surveillance and testing at this time.

Flowing creeks and waterways do not generally contain mosquito larvae.

A white cloud which dissipates quickly into the air and is invisible at that point.

No, the chemical used is specific for insects.

As a precaution, pet food should be brought inside.

No, but remember to wash your vegetables before eating them as you normally would.

No, the City of Ennis may only fog areas that are publicly owned and maintained. Private landowners are responsible for all maintenance on their own property and alleyways.

The Center for Disease Control (CDC) recommends adults wear repellent that contains 30 percent of the ingredient DEET to be most effective against the mosquitoes that carry WNV. However, lesser amounts of DEET products may be used with repeat applications during outdoor time periods as specified on the CDC website