Dealing with Mosquitoes

The Asian tiger mosquito (ATM) is a common pest around home landscapes. This small black mosquito with white markings (Figure 1) flies during the day and is a persistent biter. Its larvae can develop in almost any water-filled container. The ATM tends to stay within about 300 feet of its breeding site so homeowners can do a lot to reduce problems on their property by eliminating standing or trapped water.

Figure 1. Asian tiger mosquito (Photo: Matt Barton UK Ag Communications)

Eliminate Breeding Sites

  • Eliminate potential breeding sites by draining water that has accumulated in buckets, discarded containers, clogged gutters, pet dishes, etc. Treat standing water that cannot be eliminated using products that contain “Bti” (Mosquito Dunks) or methoprene (Mosquito Torpedo) to control mosquito larvae (wrigglers). These chemicals are available in granular or block form that are dropped into the water. Check the label to be sure the sites you want to treat are included.
  • Adult mosquitoes prefer to rest in moist, shady areas (such as dense vegetation) during the daytime. Removing tall weeds and overgrown vegetation reduces humidity and allows airflow, forcing mosquitoes to move. Residual insecticides can be applied to shrubs, hedges, and other shaded areas where vegetation removal is not practical or desirable, as well as under decks and along foundations. Example products include lawn and garden insecticides containing permethrin (e.g., Ortho Mosquito B Gone, Spectracide Mosquito Stop), cyfluthrin (Bayer Advanced Powerforce Mosquito Killer), bifenthrin (e.g., Ortho Home Defense Max), or lambda cyhalothrin (Spectracide Triazicide). Follow label directions and do not spray flowering plants.

Exclusion

  • Keep mosquitoes from entering homes by securely screening windows, doors, and porches. Swatting mosquitoes found indoors is preferable to applying insecticides.
  • Mosquitoes generally avoid drafts and turbulent air so directed fans may provide adequate protection in outdoor areas, acting as invisible screens.

Repellents

  • Repellents will help prevent bites when spending time outdoors. Many repellents contain the active ingredient diethyl toluamide (DEET) in concentrations ranging from 5% to 40%. Higher percentages of DEET provide longer protection. Low -percentage formulations (10% or less) are suitable for shorter periods outdoors (e.g., 1 to 2 hours), and are recommended for use with young children. Check the label before use.
  • Picaridin (7% Cutter Advanced) and Lemon eucalyptus oil (30% Repel Lemon Eucalyptus) provide relief for about 2 to 4 hrs. Unlike DEET-based repellents, picaridin is essentially odorless and lemon eucalyptus oil has a lemon scent. For many people, these products have a more pleasing feel on the skin.

Other Control Possibilities

  • Many consumer products claim to attract, repel, capture, or kill mosquitoes. Most of these devices do not appreciably reduce mosquito abundance or incidence of bites, or else their claims are unproven. Electrocuting devices or “bug zappers” using ultraviolet light as an attractant are generally ineffective in reducing outdoor populations of mosquitoes and their biting activity. Studies indicate that mosquitoes make up only a tiny percentage of the insects captured in such traps. The majority are moths, beetles and other harmless night flying insects.
  • Other types of mosquito traps utilize carbon dioxide, warmth, light, and various chemicals (e.g. octenol) as attractants and claim to capture tremendous numbers of adult mosquitoes. Such devices can be quite expensive. Performance claims to the contrary, such traps seldom reduce populations of biting mosquitoes on a property or the frequency of bites. In some situations, they could even attract more mosquitoes into the area they were meant to protect.
  • Advertisements for portable electronic devices using high frequency, ultrasonic sound routinely appear in magazines, claiming to keep mosquitoes and other pests at bay. Some supposedly repel mosquitoes by mimicking the wing beat frequency of a hungry dragonfly. Scientific studies have repeatedly shown these devices to be of negligible benefit in deterring mosquitoes and reducing bites. Save your money, as these devices seldom, if ever, provide any appreciable measure of protection.
  • Citronella oil does have mosquito-repelling properties and the scented candles can provide some protection. For maximum effect, use multiple candles placed close (within a few feet) of where people are sitting. A single candle located at the center or edge of a picnic blanket probably will not provide much benefit other than atmosphere.
  • Mosquito-repellent plants, garlic, and other oft-advertised botanical products generally are ineffective.

 

By Lee Townsend, Extension Entomologist

 

 

 

Posted in Human Pests