Mosquito Population Expands After Wet Weather


With all this rain, experts are anticipating a significant increase in the state’s mosquito population.  Even as this is being written, mosquito populations are booming throughout the state and will likely not go away anytime soon after all our rains and flooding.

With the mosquitoes, health departments are monitoring closely an increase in mosquito vectored disease.  And humans are not the only ones to suffer from mosquito-borne diseases, AgriLife Extension experts noted.

Mosquitoes can also be vectors for dog heartworm.  An infected mosquito can pass tiny heartworm parasites on to any uninfected dog it bites. Heartworm causes lasting damage to heart, lungs and arteries, and can affect the dog’s quality and length of life.
In addition, horses are susceptible to several encephalitis diseases, including West Nile virus, and should be vaccinated every year.

To control mosquitoes effectively and economically, everyone should understand their basic life cycle and be familiar with the important mosquito types. Mosquitoes can be divided into two groups based on where they lay their eggs. For example, floodwater mosquitoes lay eggs on the ground in low spots, and these eggs hatch when it rains and the low area fills with water.

With the unusually high May rainfall, these mosquitoes are common now and likely to remain so during the duration of the rain. Floodwater mosquitoes are good fliers and can travel many miles from their breeding sites in temporary pools, roadsides and low lying areas.

There is little people can do on their own property to protect themselves from floodwater mosquitoes, other than stay indoors or wear repellent.

We have more control over other mosquitoes that breed in containers and live closer to town. Container breeding mosquitoes include some of the most significant species that may negatively affect human health, including the common house mosquito.

Entomologists referred to what they called “the four D’s” as a general means for people to help manage mosquitoes and protect against bites. These are:

  • Dusk/Dawn – Avoid being outside when mosquitoes are searching for a blood meal, which is usually in the early morning hours and just before the sun goes down. While some species are daytime biters, most prefer to feed at dusk and dawn.
  • Drain – Empty standing water from “containers” around your home and work areas, such as buckets, wheelbarrows, kiddie pools, toys, dog bowls, water troughs, tires, bottles, etc. Make improvements that allow standing water to run off following rains.
  • Dress – If out during mosquito feeding hours, wear long sleeves and pants in plain colors. Avoid attracting them by wearing excessive amounts of perform or aftershave.
  • Defend – Any time you go outside for an extended period of time, wear an insect repellent.

In addition, mowing tall weeds and grass can help eliminate some mosquito resting areas.

When mosquito populations are high, labeled contact insecticides can be used to knock down adults. For greatest effectiveness, sprays should be directed to shady mosquito resting areas. In addition, insecticide-based misting systems can be effective short-term, but repeated applications can cause insecticide resistance or be harmful to non-target insects and may result in loss of control. These systems are most likely to be effective if timers are set to spray when mosquitoes are most active.

Mosquito dunks containing insect growth regulators or Bti, the mosquito larva’s bacterial natural enemy, can be used in water that cannot be dumped or drained to reduce mosquito populations.

Products that apply a surface film or oil on the water can also be used to reduce larval mosquito and pupal populations by preventing them from getting air through their breathing tubes.  The use of films or oils should be limited to locations without any other organisms, since it will prevent oxygen to the non-target organisms as well.

According to most experts, insect repellent is still the best overall defense. If you keep a bottle or can of repellent just outside their doorway to remind yourself to spray exposed skin, even if you plan to be outside just a short while.  Keeping repellent in your car is a very good idea too.

The entomologists agreed that repellents with DEET remain the gold standard for protection. DEET has some of the best persistence. However, there are good alternatives to DEET if you aren’t going to be outside very long. The natural repellent, oil of lemon eucalyptus, is a good alternative to DEET for those who prefer an organic product. The most important thing is to find a repellent that works for you and to use it.

For more information about where mosquitoes can breed, and how to identify mosquitoes, go to AgriLife Extension’s Mosquito Safari website,

Educational programs of the Texas AgriLife Extension Service are open to all people without regard to race, color, sex, disability, religion, age, or national origin.

Cary Sims is the County Extension Agent for agriculture and natural resources for Angelina County. His email address

Cary Sims
Cary Sims is the County Extension Agent for agriculture and natural resources for Angelina County. His email address is Educational programs of the Texas AgriLife Extension Service are open to all people without regard to race, color, sex, disability, religion, age, or national origin.

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