Health Department


Chauncy Williams, R.E.H.S./R.S - Director 

Department of Health Services


Mailing Address:
P.O. Box 220
Ennis, TX 75120

Physical Address:
105 S. Preston Street

Ennis, TX 75119

Ph: (972) 875-6442
Fx: (972) 875-8540

Mosquito FAQs



How can I protect myself against mosquito bites?

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. 

Can small children apply chemicals to their skin? What is recommended?

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. 

How can I find out what cases have been reported?

 Please visit the Texas Department of State Health Services West Nile Virus website for information regarding this area. 

How does the City determine when to spray?


  • 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. 


What days of the week does the City spray?

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

What weather conditions prevent the City from spraying?

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

How long does the spray last?

The approximate duration is 1 hour after it is dispensed.

I have asthma -- will the chemical from the spray harm me?

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

Do I need to bring in my pets?

As a precaution, pets should be brought inside.

Do I need to cover my pool?

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

I have children - do I need to clean the outdoor toys after spraying?

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

Does the City spray on school property?

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

What is the City of Ennis doing about West Nile Virus?

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.

What precautions should I take when the City does spray?

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. 

What can I do to help eliminate mosquitos from my yard?

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.

Will birds be shipped for testing?

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.

I have a creek that backs up to my house. Will mosquitoes breed in the water?

Flowing creeks and waterways do not generally contain mosquito larvae.

What does the spray look like?

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

Will the spray harm or kill the birds and squirrels?

No, the chemical used is specific for insects.

Do I need to bring in my pet food?

As a precaution, pet food should be brought inside.

Will it harm my garden?

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

Will the City of Ennis fog areas on private property or alleyways?

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.

What insect repellents should I use?

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