Mosquitoes are more than just annoying – they can carry serious diseases that can affect you, your family, your pets and your livestock. Learn how to

Hays County Mosquito Surveillance Program and
Tips on Mosquito Prevention

Hays County Development Services (HCDS) is providing mosquito surveillance within the county to monitor and track mosquito-borne illnesses. Some mosquitoes have the capability to transfer potentially deadly diseases – known as arboviral diseases – to humans. HCDS is collecting mosquitoes in order to determine which areas are harboring disease-carrying mosquitoes. HCDS will set up collection traps to capture samples of several species of mosquitoes that will be sent to the Department of State Health Services in Austin for identification and determination of the type(s) of illness the mosquitoes could be spreading. Monitoring species, mosquito density and geographic breeding sites will provide critical early predictive data to help monitor, prevent and combat mosquito populations and mosquito-borne illnesses.

HCDS uses the Centers for Disease Control and Prevention (CDC) gravid-trapping method to collect mosquitoes. This trap is designed to attract female mosquitoes that are ready to lay eggs. The trap uses a fan to draw in mosquitoes that approach the liquid in the bottom of the bucket and keeps them in a collection bag until the trap is collected. Collection is typically carried out from May until November throughout Texas.


 Hays County Mosquito Surveillance Video

 Hays County Mosquito Surveillance Audio Only



A typical CDC gravid mosquito trap. If you see one, please do not touch or disturb it. Hays County will place and monitor 6 traps throughout the County during prime mosquito season. See the mosquito trap map here.

Viruses of concern

West Nile virus, St. Louis Encephalitis, Eastern Equine Encephalitis, Western Equine Encephalitis, Dengue virus, La Crosse Encephalitis, Chikungunya virus and Rift Valley Fever virus.

Symptoms of infection

Most infections do not result in any symptoms. Mild cases may occur with only a slight fever and/or headache and body aches and resolve with no complications. Severe infections are marked by a rapid onset, headache, high fever, disorientation, tremors, convulsions, meningitis, encephalitis, flaccid paralysis, coma or death. Symptoms may occur days to weeks after a bite from an infected mosquito. Health care providers can provide supportive care but there is no specific treatment available for arboviral infections.

Who can be infected?

Anyone can get an arboviral infection, but young children and the elderly may be more susceptible. Most arboviral infections are spread by infected mosquitoes, but not all mosquitoes have these viruses. Only female mosquitoes will take a blood meal and have the potential to pass along the harmful viruses. Migrating birds may aid in transmitting disease but humans cannot become infected with arboviruses directly by birds, only by mosquitoes. Note that while some jurisdictions participate in collecting and testing dead birds in order to track these diseases, Hays County does not. For more information on dead bird testing, visit this Texas A&M University pdf.

What should I do to prevent mosquitoes and in turn, infection?

Use the four D’s: Drain, Dress, Dusk, DEET to prevent mosquitoes from biting you.
o Drain all free standing water. Mosquitoes can lay eggs in less water than fills a bottle cap!
o Dress in long sleeves and long pants so they can’t bite you as easily.
o Dusk (and Dawn) is when these mosquitoes are out feeding. Take extra precautions when you go out at these times.
o DEET has been tested and approved by the Environmental Protection Agency. There are other approved insect repellants but each formulation may provide varying results. For a complete list of repellants and their repellency visit

If you have standing water such as ponds and large animal water troughs, Mosquitofish (Gambusia affinis) can be used as a biological mosquito control instead of using insecticides. These fish are an attractive and effective alternative. Refer to a pet supply store for more information on obtaining compatibility charts and proper care of Mosquitofish.

How many fish do you need?
Ornamental ponds: 6-10 fish per pond (depending on size) Out-of-order swimming pools: 15-30 fish per swimming pool Animal watering troughs: depends on the size of the trough. Ask your supply store for more information if the above dimensions do not provide an adequate example.

Download additional information for your neighborhood, business, school, etc.
Target the Source (Eng) Mosquito Flyer (Eng) Mosquito Flyer (Sp) Mosquito Door Hanger (Eng) Mosquito Door Hanger (Sp) Fight the Bite Logo (Eng) Combata las Picaduras Logo (Sp)


Questions about Hays County Mosquito Surveillance? Contact

Eric Van Gaasbeek, Registered Sanitarian, 512-393-2187
or Eric Schneider, Registered Sanitarian, 512-393-2185