Mosquitoes, Zika virus and other considerations
Gardeners get bitten by mosquitoes, it’s a given. And if you are a gardener you may be wondering if you should be concerned about Zika virus, which can be contracted through the bite of a mosquito. In Michigan and much of the northeast the mosquitoes that carry Zika virus, Aedes aegypti and A. albopictus are not yet common. There are concerns however, that other mosquitoes may eventually carry it. And with a warming climate these mosquitos may eventually work northward.
There are other mosquito carried viruses such as chikungunya, dengue, West Nile Virus, and several other encephalitis producing diseases, even malaria and yellow fever to be wary of too. West Nile cases occur almost every year in Michigan. These diseases are serious, and can cause death. As a gardener you should do all you can to prevent mosquitoes and to keep from being bitten by them. This is not the time to trust your health to home remedies and mixes. And it would be wise to support a mosquito control program in your county, even spraying with pesticides for adult mosquitoes.
To keep from getting bitten the CDC suggests using these products on your body and clothing. Products with DEET including Off!, Cutter, Sawyer, and Ultrathon brands. Deet is the most studied insecticide in the world and has been used for over 40 years. It is a synthetic chemical product but if label directions are followed it is extremely safe.
Some other recommended mosquito repellants are products with Picaridin, also known as KBR 3023, such as Bayrepel, and icaridin, Cutter Advanced, Skin So Soft Bug Guard Plus. Products with IR3535 such as Skin So Soft Bug Guard Plus, (another formula), Expedition, and SkinSmart are also good. Products with Oil of lemon eucalyptus (OLE) or para-menthane-diol (PMD) such as Repel are fairly effective.
Along with repellant, wear long sleeves and pants when working in mosquito infested areas, especially at dawn and dusk and on cloudy days. Some mosquitoes bite right through clothes so a repellant safe to use on clothing should be sprayed over clothing in high population areas.
You may want to avoid floral scents on your body and clothes and drinking alcohol before going out into mosquito areas. Research has indicated these things attract more mosquitoes.
To prevent mosquitoes from hatching
Empty out all standing water around the home. Mosquitoes need water to lay their eggs and it only takes 3-10 days to hatch and grow a new brood of mosquitoes. Empty bird baths, pet dishes, stock tanks, and wading pools at least every other day. Pick up or empty anything in the yard that holds water, such as toys or trash.
Fill in low spots in the yard that hold water with soil. Fill holes in trees that collect water with sand.
Clean clogged gutters. Make sure rain barrels have a screened top or are treated with Bt.
Put screens on septic vents or other sewer vents.
If water cannot be emptied or drained treat the water with mosquito controls containing Bt, a natural organism that harms only mosquitoes. You can find the doughnut shaped briquettes in garden stores. Fish in ornamental ponds help control mosquitoes and Bt won’t hurt them.
Make sure all windows and doors have screens that are in good shape.
Getting rid of adult mosquitoes
Keep grass and weeds trimmed around homes and outbuildings. Adult mosquitoes rest in vegetation during the day and you don’t want to encourage them. Weedy areas can be sprayed with insecticides like pyrethrins or 5% malathion to kill adult mosquitoes but such spraying also kills many beneficial insects. Many counties have mosquito control programs but these generally spray along the roads. You may want to spray around your home if it’s far from the road.
You have to weigh the pros of spraying pesticides with the cons of reducing helpful insects. If mosquitoes are very numerous and diseases carried by mosquitoes have popped up in the area it’s probably wiser to spray.
What doesn’t work for mosquitoes
There are no plants that you can just sit on the patio or plant around the house that will effectively repel mosquitoes, despite all those advertising claims. No objective studies have ever found a plant that will do that. NONE! The chemicals that repel insects must be extracted from the plants in some way and applied to the skin. Even burning the chemicals in a candle or as incense has little effect. Most studies find that burning a plain candle is just as effective as burning a citronella one.
The citrosa plant (Pelargonium citrosum ‘van Leenii’) sometimes advertised as Mosquito plant, Mosquito Shoo, and other assorted names, is useless as a mosquito repellant. No plant repels mosquitoes just by sitting near you. This plant is actually a scented leaved geranium and it does have a very small amount of citronellol in it just as many other plants do. You would have to crush the leaves and rub them on your skin for it to have even the most fleeting effect.
Thousands of these plants are sold each year, even though they don’t work and don’t even have a pretty flower or form to redeem them. Common Lemon Balm has 3-4 hundred percent more citronellol than Citrosa, but don’t expect it to repel mosquitoes.
Citronella has some repellant properties. The problem with using citronella as an insect repellent is that it must be used in a very strong concentration and the effect wears off quickly. Citronella is only effective if applied to the skin. That causes another problem, many people are allergic to strong concentrations or their skin becomes irritated. Citronellol is absorbed through the skin and some studies are linking exposure to the chemical to liver damage and cancer.
Most citronella products you buy at the store are so diluted that they contain almost no active ingredient. It is a waste of money to buy citronella oil or candles to burn unless you just like the smell. No other products you burn to make smoke are any more effective.
Some plants have chemical ingredients that when extracted, do have mosquito repellant properties. The problem is that the active ingredients are costly and hard to extract or they have some serious side effects. A chemical found in mints for example, is effective as an insect repellant but some studies have found kidney damage and genetic damage when it is used.
Using essential oils and other home concocted mosquito repellants may have a fleeting repellant effect. They wear off rapidly and need to be re-applied frequently. And because they are “natural” does not mean they are safe. Many of these home concoctions have oils and other extracts that have serious side effects. You don’t want to avoid mosquitoes by getting liver or kidney failure.
Other things that do not work to control mosquitoes are ultrasonic devices and light traps. Some traps using carbon dioxide and pheromones show promise but are expensive and each trap appeals to different species of the hundreds of mosquito species in the US. They haven’t been very effective on many species of mosquitoes that are most likely to carry diseases.
In short – don’t trust your life to these home remedies and so called natural repellants. Use something with proven, scientific based research backing it up, not just some claim by a salesperson. Because it’s what’s at stake- your life.