This article was originally produced on August 26, 2001 as a bi-monthly news column for the Vero Beach Press Journal.
Date of release: August 22, 2001
Daniel F. Culbert, County Extension Agent
Repellants for Mosquito Protection
Whether you are an avid gardener or outdoor sports enthusiast, summer rains and the emergence of mosquitos have made many local residents a bit slap happy. In this time of heightened concern about mosquito bites and the diseases people can contract from mosquito vectors, a review of mosquito management in our Florida Yards may be a timely issue.
Many county Mosquito Control Districts are working to reduce the severity of the problem on a broad scale. However, homeowners can supplement these public health efforts with a few actions on their own properties that can reduce the problem. With a little dab of repellants when outdoors and some common sense approaches to outdoor activity, life can go on. Information for today’s column comes from University of Florida Extension Specialist Roxanne Rutledge and Entomologist Jerry Butler.
DEET is Best Repellant
Research has shown that the most effective way to avoid mosquitoes is to stay indoors when their biting activity is at its peak, between dusk and dawn. Even when you are wearing appropriate clothing (loose; long sleeves and pants; light in color), don’t venture out doors unless you use an appropriate mosquito repellant.
Research has shown that the most effective products to use contain a chemical with a long name: N,N-diethyl-meta-toluamide - the full name for this pesticide. We call it DEET for obvious reasons. It repels mosquitoes, no-see-ums, ticks and several other biting critters. They’ve been in use for nearly 50 years. Repellents containing DEET are available in many forms and strengths. In general, inexpensive products contain less than 10% DEET, while the more expensive ones have more than 20% DEET. Depending on the product and the exposure, these repellents will provide protection from mosquito bites for 2 hours up to 12 hours.
What product do you choose, and why? If a little DEET is good; is a lot of DEET better? Not necessarily. In tests done by the Army, repellents with 30-40% DEET worked twice as well as repellents with 75% DEET. Concentrations over 50% should not be used. DEET is better off applied to clothing rather than directly to the skin, and should be kept away from eyes or bruised skin. As with the use of any pesticide; read and follow the label directions: they are written and researched to allow for the safe and effective use of these products.
Alternatives to DEET
Concerns about the use of DEET, especially on children and others that are sensitive to this chemical, have resulted in investigations of alternatives. Other issues with DEET are that it can effect certain kinds of plastics and textiles. Safety concerns over have forced manufacturers to reduce the amount of DEET in various products during the past 15 years.
There are many repellents that do not contain DEET that can be applied to the skin. Products with citronella (an oil extract from a lemon-scented grass) or eucalyptus can be purchased, frequently in health-food or camping/outdoor stores. Avon's Skin-So-Soft© , is widely used as a repellent but it is largely ineffective. However, most non-DEET products need to be reapplied frequently. In general, research shows that these products are less effective than DEET.
Recently UF Entomologist Dr. Jerry Butler has developed an effective non-DEET repellant that is becoming more widely available for those with concerns with DEET sensitivity issues. The new products contain an oil extracted from plants. The active ingredient is geraniol, derived from lemon grass, mints and other plants. The product has been labeled "generally regarded as safe" by the Environmental Protection Agency. Applied to the skin, it provides almost four hours of protection against a wide range of biting insects, including flies, fire ants, mosquitoes, ticks and biting midges, often called no-see-ums.
Butler's geraniol repellent is patented by UF and licensed to Naturale, Ltd., Great Neck, N.Y., which is marketing the products under the registered trademarks of MosquitoSafe, TickSafe and FireAntSafe. I’m told that it is marketed in Rite-Aid Drug stores, which are not in our area. Consumers interested in obtaining this repellant can check with local health food stores or outdoor outfitters.
There is no scientific evidence that eating garlic, vitamins, onions or any other food will make you repellent to mosquitoes. The attractant level of each individual to biting arthropods is based on a complex interaction of many chemical and visual signals. Certain foods in certain individuals may effect their individual attractiveness to biting arthropods, for better or for worse. If it works for you, or you think it works for you, do it.
Reducing flying mosquitos
There are many other products on the market that are not effective as repellents or mosquito control devices. The popular and expensive bug zappers are not effective for controlling biting insects. Yes, they kill some mosquitoes, but they kill many more beneficial insects, often in huge numbers. The light of the zapper attracts more mosquitoes into a yard than would be present if the zapper was absent.
Birds and bats, while desirable for other reasons, will not reduce the number of mosquitoes in your yard. Even the Purple Martin Conservation Association rejects the idea that Martins control mosquitoes. Bats do eat mosquitoes, but the bulk of their diet is consists of plant feeding insects rather than mosquitoes.
Space sprays and aerosols may provide brief but temporary relief from these biting beasties, but look carefully to see if they are labeled for indoor use. Candles with oil of citronella may be of value when there are windless conditions. So short of living in the arctic winters or becoming an indoor hermit, how can you get rid of mosquitos?
Inspect for Breeding Sites
Most of the mosquitoes that trouble homeowners and visitors cannot be eliminated through individual efforts, but instead, must be controlled through an organized effort. There are many Mosquito Control Commissions in Florida, tax-supported agencies that specialize in large area mosquito management by permanently impounding water and ditching and draining swampy mosquito breeding areas. They also treat breeding areas to kill larvae and spraying spaces to kill adults. They have leaned how to do this with the least possible impact to natural areas.
However, reduction of nuisance mosquitos is also everyone’s responsibility. Have you walked around your yard recently and noticed that an old pot has filled up with rainwater? Are you changing the water in your birdbath? Are there old tires in the ditch behind your house? Some other places to inspect are gutters, pools, boats, plant that hold water, and low spots in the yard. If your snowbird neighbor has similar situations, ask the folks that mow their yards to be on the lookout for these kinds of mosquito breeding areas.
Dr. Roxanne Rutledge works in Vero Beach at the Florida Medical Entomology Laboratory. She is part of a state-wide task force that is dealing with the West Nile and Eastern Equine Encephalitis situation that has been in the news recently. They have created a great website to learn about mosquitos, and it includes on-line games that can be used to identify solutions to breeding areas that often do not involve pesticides. Check out the Encephalitis Information System at http://eis.ifas.ufl.edu.
f you need additional information on mosquito repellants, visit your county Master Gardeners, or call or stop by your county Extension office. For those with other questions about Florida Yards, contact me - my phone number is 863-763-6469 and you can send e-mail to firstname.lastname@example.org.
eturn to Dan Culbert's webpage
Trade names, where used, are given for the purpose of providing specific information. They do not constitute an endorsement or guarantee of products named, nor does it imply criticism of products not named. The Florida Cooperative Extension Service - Institute of Food and Agricultural Sciences is an equal opportunity/affirmative action employer authorized to provide research, educational information, and other services to individuals and institutions that function without regard to race, color, sex, age, handicap, or national origin. Florida Cooperative Extension Service / IFAS /University of Florida. Larry A. Arrington, Dean. Last update: 06/09/2005 . This page is maintained by Dan Culbert