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.
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