Ask the Contractor: Mosquito 101

Eliminate all of the ‘standing’ water around your home. (File Photo)

Eliminate all of the ‘standing’ water around your home. (File Photo)

With the monsoons approaching, that means standing and pooling water and that means mosquitos.

Mosquitoes are the most important insect pests that affect the health and wellbeing of humans and domestic animals worldwide. They can cause a variety of health problems due to their ability to transfer (vector) viruses and other disease-causing pathogens, even in the arid Southwest U.S. Female mosquitoes usually require a blood meal from a vertebrate animal for egg production.

Different species of mosquitoes have particular host animal preferences for blood-feeding. Some specialize on birds, some on humans, and still other mosquitoes feed on a wide range of hosts. During feeding the mosquito injects her saliva into the host’s skin, which can generate an itchy reaction.

If she has acquired a disease pathogen from an earlier blood meal, and sufficient time has elapsed for the pathogen to develop inside the mosquito (incubation period), the pathogen may be transmitted to a new host. Incubation periods are different for each pathogen and can range from days to weeks.

Understanding the basics of mosquito biology will help you manage mosquitoes and related disease risks. All mosquitoes must have water to complete their life cycle, although some species require very little water and can develop in a thin moisture film.

The mosquito life cycle is an example of complete metamorphosis. There are four distinct stages in the life of a mosquito: egg, larva (aquatic feeders), pupa (aquatic non-feeders) and adult.

They begin life as eggs. Female mosquitoes usually lay eggs a few days after acquiring a blood meal. The eggs are laid on the surface of water, on the sides of containers, or on damp soil.

Mosquitoes need water to complete their life cycle. Humans create a lot of opportunities for mosquitoes to exploit. Many of us have mosquitoes developing in our neighborhood and even in our own backyards. Standing water left from monsoon rains or irrigation water will support increasing mosquito populations. Stagnant water in neglected swimming pools is another ideal habitat for many species, though mosquitoes cannot live in a well-maintained swimming pool. Some important vectors breed in “cryptic” breeding sites, utilizing very small amounts of water in tree-holes, artificial containers and even leaf axils.

The most effective strategy for mosquito management is prevention. The best way to prevent mosquito-borne diseases is to eliminate their breeding sites in the first place. Here are some tips on what you can do to manage mosquitoes and eliminate mosquito-breeding sites around you.

  1. Eliminate standing water in plant pots, bird-baths, fountains, tires, tarpaulins covering boats or other objects, and backyard trampolines and other items (Fig. 13A, D). Check for standing water after every rain or at least once per week; twice per week is ideal.
  2. Remove unnecessary clutter. Keep rain gutters free of leaves and other debris that prevent water from draining. Store boats, canoes and other objects so they do not collect rainwater. Saucers placed under potted plants are a favorite breeding site. They should be drained after watering, or removed entirely. If eggs are suspected, they need to be scrubbed away, otherwise they remain viable for months, and will hatch at a later date.
  3. Repair water leaks (leaky pipes, sprinkler systems, and outside faucets). Correct drainage problems in yards and report drainage problems in ditches, etc. to the appropriate jurisdictions for correction.
  4. Empty water containers for pets regularly and check livestock watering troughs and tanks mosquito eating fish can be added to large (undrainable) water troughs for livestock and horses.
  5. Cover rain-collection barrels with insect exclusion netting.
  6. Add gambusia (mosquito-eating fish) into personal ponds or stagnant swimming pools to reduce the number of mosquitoes. It is very important to avoid releasing gambusia into natural waterbodies, as these are voracious predators, and can displace native fish.

When outdoors, consider the following safety tips:

  1. Wear light-colored clothing with loose fitting long-sleeves, long pants and socks. Use protective clothing when exposure to mosquitoes cannot be avoided.
  2. Properly apply insect repellent even if you are outside for just a short period of time, and share your insect repellent with those around you. For additional help selecting which repellent is right for you, go to the EPA search page: http://cfpub.epa.gov/oppref/ insect/#searchform.
  3. Use a DEET-containing product or a good non-DEET alternative http://www.ncbi.nlm.nih.gov/pmc/articles/ PMC4667684/pdf/iev125.pdf and, if you are outside for more than a few hours, reapply repellent frequently.

The higher the temperature, the more frequently you must reapply repellent for it to be effective.

• Apply repellents only to exposed skin and/or clothing (as directed on the product label). Do not use under clothing. Apply over sunscreen after it has dried.

• Never use repellents over cuts, wounds, or irritated skin.

• Do not apply to eyes and mouth, and apply sparingly around ears. When using sprays do not spray directly onto face; spray on hands first and then apply to face.

• When using on children, apply to your own hands and then put it on the child.

• Do not apply repellent on babies under 2 months old. Insect repellents are a kind of pesticide, please read the label and follow instructions. Most products specify the youngest age allowable for a given product.

• Do not spray in enclosed areas. Avoid breathing a repellent spray, and do not use it near food.

• The best approach to controlling mosquitoes is prevention, searching for and eliminating breeding sites of standing water in your indoor and nearby outdoor environment and cooperating across neighborhoods, communities and with local district efforts.

• Mosquito-borne illness can be avoided by preventing mosquito bites.

• A single female can lay hundreds of eggs over her lifetime.

• Many mosquito species can develop from egg to biting female adult in under a week.

• Not all species bite humans; some prefer birds, others prefer horses. But even those that prefer birds will feed on humans if the opportunity arises.

• Only females take a blood meal; both males and females feed on plant nectar.

• Some mosquito species fly considerable distances, 20 miles or more. Some species tend to remain close to their larval habitats.

• Adult females can survive several weeks, some months.

• Mosquitoes are responsible for more human mortality around the world than any other living creature.

Sandy Griffis is executive director of the Yavapai County Contractors Association. Email your questions to her at ycca@cableone.net or call 928-778-0040.