Mosquito control, West Nile or Zika virus in DFW: Ask Magnolia Fisheries about an Integrated Mosquito Management Plan.
The discussion below is intended to educate pond owners on mosquito control and reduction of larval mosquito populations. For maximum control, the procedures outlined in this plan should be included as part of an Integrated Mosquito Management Plan (IMMP) that attacks their population through multiple methods. Examples of other methods include: chemical sprays and fogs that target adult mosquitoes, draining standing water, and educational efforts regarding personal safety measures (DEET, long sleeves, avoiding exposure at dusk and dawn, etc).
Our primary service to you is aquatic vegetation control and supplemental surface water movement. Management of aquatic growth and/or installation of surface fountains and aerators eliminate stagnant water, thereby reducing the possibility that successful mosquito reproduction will occur.
Biology and Implications for Mosquito Control
Mosquitoes undergo four stages in their life cycle: egg, larval, pupal, and adult. In most species, the egg, larval, and pupal stages are spent underwater where they are harmless to humans. These submerged stages are the ideal time to implement control measures since they are concentrated in a somewhat manageable aquatic environment.
Not all mosquitoes breed in permanent or semi-permanent water. “Flood water mosquitoes” lay eggs on dry areas that are likely to be temporarily submerged after a rain event. This is important because actions to control breeding in relatively permanent water will not control these “floodwater species”. It should be mentioned that Culex quinquefasciatus, the most common species to carry the West Nile virus, is not a “floodwater” variety, and therefore can be controlled during the aquatic life-cycle stages.
Population control using martins, dragon flies, bats, and frogs is widely discussed on the internet. However, there are no current scientific studies to validate significant control using these methods.
Larval Control in Lakes, Ponds, and Streams
Mosquitoes require relatively calm water to breed. Mosquito larvae extend a “snorkel-like” breathing tube to the surface of the water. Any amount of surface agitation or wind action will drown them. Therefore, wind and wave action, currents, or any other water surface disturbance physically restricts their capability to successfully complete their life cycles. If your water has a floating fountain or aerator, the added water movement will hinder successful breeding.
If mosquitoes are able to make it to the larval and pupal stages, an onslaught of natural predators greatly reduce their numbers. The Gambusia (mosquito fish) is a native Texas fish common to essentially all North Texas waterways. Gambusia are so adept at consuming larval mosquitoes that they are often introduced for the sole purpose of mosquito control. Common sunfish and other small fish are also very effective at eliminating the aquatic stages of mosquitoes. Most ponds in North Texas already contain high numbers of bluegill sunfish.
Eradication of any tall vegetation adjacent to ponds and lakes will eliminate the daytime resting habitat of adult mosquitoes. This makes your pond less attractive to breeding adults. Likewise, routine management of algae and aquatic vegetation will reduce the amount of stagnant water present in your pond.
Mosquito Control Recommendations
The most effective method of mosquito control is to find and eliminate their breeding sites. The Dallas County Health Department recommends that homeowners should take the following steps to prevent breeding on their own property:
- Destroy or dispose of tin cans, old tires, buckets, unused plastic swimming pools or other containers that collect and hold water. Do not allow water to accumulate in the saucers of flowerpots, cemetery urns or in pet dishes for more than 2 days.
- Clean debris from rain gutters and remove any standing water under or around structures, or on flat roofs. Check around faucets and air conditioner units and repair leaks or eliminate puddles that remain for several days.
- Change the water in birdbaths and wading pools at least once a week and stock ornamental pools with top feeding predacious minnows. Known as mosquito fish, these minnows are about 1 to 1.5 inches in length and can either be purchased or seined from local streams and creeks.
Ornamental pools may be treated with biorational larvicides or BTI’s (Bacillus thuringiensis subsp. Israelensis) or methoprene (IGR) products under certain circumstances. Commercial products called “Mosquito Dunks” and “Mosquito Bits” containing BTI’s can be purchased at many home/garden stores for homeowner use.
Recently, Zodiac, a division of Wellmark International, developed a “Preventative Mosquito Control” (PMC) product that kills them in their developing stages using insect growth regulator (IGR) technology. Like Mosquito Dunks, Zodiac’s “Preventative Mosquito Control” can be found at many home/garden and pet specialty stores.
- Fill or drain puddles, ditches and swampy areas, and either remove, drain or fill tree holes and stumps with mortar. These areas may be treated with the above BTI or methoprene products also.
- Eliminate seepage from cisterns, cesspools, and septic tanks.
- Eliminate standing water around animal watering troughs. Flush livestock water troughs twice a week.
- Check for trapped water in plastic or canvas tarps used to cover boats, pools, etc. Arrange the tarp to drain the water.
- Check around construction sites or do-it-yourself improvements to ensure that proper backfilling and grading prevent drainage problems.
- Irrigate lawns and gardens carefully to prevent water from standing for several days.
- If ditches do not flow and contain stagnant water for one week or longer, they can produce large numbers of mosquitoes.
Most mosquito activity is at dawn and dusk. If possible, avoid outdoor exposure at those times. Always wear long sleeves and pants during peak exposure times. Apply liberal amounts of an insect repellant containing DEET.
“Why Can’t You Spray Them In OUR Neighborhood?”
Federal and State laws make it illegal to spray or broadcast insecticides “in, around, or over water”. Many municipalities have stopped fog spraying and there are a very limited number of private pest control operators that work on the homeowner association level. Magnolia Fisheries provides Mosquito Dunks (BTI’s) and place them in stagnant water areas for our existing customers during those times of the year when mosquitoes are active.
Mosquito Control Summary
Roughly 95% of all adult mosquitoes are hatched in standing pools of water that collect in ditches, culverts, flower pots, etc. These would be the ideal places to place BTI dunks. Keep in mind that mosquito dunks only attack the larval stage. Since they do not attack adult mosquitoes, residents should realize that BTI’s do not automatically equate to fewer pests. This method is a biological control agent used to “hinder” mosquito production, but will never “eradicate” it.
The good news for urban pond owners is that well managed ponds and lakes are typically NOT the source of successful mosquito reproduction. Routine aquatic vegetation treatments and the addition of fountains or aerators make it difficult for them to complete their life cycle to adulthood. If the larval stages are not drowned by fountains/wave action, they are usually quickly eaten up by natural predators. As a result, simply tossing BTI dunks into well managed ponds could be a waste of resources.
If you are concerned about mosquitoes in your urban pond, call Magnolia Fisheries. We will evaluate your pond and advise if an IMMP is required to comply with health regulations.
For additional information on West Nile Virus and Mosquito Control from Dallas County Health and Human Services, follow this link.