Summer Harvests – Rainfall and Mosquitoes
According to the Farmer’s Almanac and AccuWeather, Summer 2020 will bring the Mid-Atlantic above average rainfall and lots of humidity (and a few heatwaves in July/August so brace yourself for a ‘sizzle and drizzle’ summer). The abundant rainfall will be good for gardens and other outdoor projects.
All that free-falling water could mean good things for your water bill which has probably been higher than normal thanks to the coronavirus shutdown. This article is an update from 2016 on the effective use of rain harvesting strategies and prevention of a most unwanted summer harvest – mosquitoes.
Rain creates puddles and pools where they shouldn’t be; humidity makes it harder for them to evaporate. A single ounce of standing water makes the perfect nursery for mosquitos, a summer visitor that has in recent years become more than a nuisance.
In 2016, attention was on the Zika virus being brought home by travelers. The potential threat of it being spread by mosquitoes from those travelers to non-travelers never materialized. Let’s hope 2020 won’t be the year that happens, either.
Scientists also considered other ways infection can take place, such as through blood transfusions. Back then, state and other government agencies rolled out Zika information to raise awareness, not cause alarm. Forewarned…
The two likeliest mosquitoes to carry Zika in the Mid-Atlantic also spread its cousins – chikungunya, dengue, and West Nile.
Eggs can hatch after a dormant period so it’s important to watch out for damp areas inside your home and out. Being weak flyers, Aedes bite close to where they hatch. For that reason too, a fan makes a useful tool for keeping them at bay.
Viruses
Like Zika, these viruses have been reported in the Mid-Atlantic but are imported by travelers returning from the Americas, Africa, or Asia.
- Chikungunya is a virus where fever and joint pain are the most common symptoms. A person could also experience headache, muscle pain, joint swelling or rash. As of January 2016, all cases of the virus in the US were found in travelers to affected areas of the world. There is no vaccine and treatment consists of symptom management.
- Dengue fever symptoms are high fever, headache, vomiting, muscle and joint pain, and skin rash. It can develop into hemorrhagic fever or shock syndrome which are more serious, possibly fatal, conditions that cause bleeding and low blood pressure.
- West Nile can go undetected in 70 to 80 percent of those who become infected. Fever, headache, body aches, skin rash, and swollen lymph nodes are symptoms most likely to be experienced. In a minority, stiff neck, sleepiness, disorientation, coma, tremors, convulsions, and paralysis can occur.
Animals
- West Nile can be transmitted to horses.
- Dogs and cats are susceptible to heartworm disease.
- DEET should never be used on pets; it is extremely toxic.
- Only use repellants specifically made for animals to prevent adverse reactions.
To minimize the likelihood of being bitten
- Cover up as much as possible, especially arms and legs.
- Use mosquito repellant. Read the label so you know how often to reapply.
- Avoid standing water. Outdoors, water tends to pool in gardens, around rain barrels, on patios or sidewalks, and even on porches. Indoors, be alert to areas that can hold dampness like shower or window tracks, corners, or plant stands. The yellow fever mosquito likes being indoors, too.
Mid-Atlantic Mosquito Resources
Strategies to discourage the growth of mosquitoes
- Dispose of any container – tire, bucket, pot – that can collect water.
- Fill in hollow stumps or tree rot holes.
- Drill a hole in the bottom of a tire used as a swing to allow water to escape.
- Refresh water each week in birdbaths, watering troughs, plant trays, and non-aerated ponds.
- Store wheelbarrows upside down.
- Add fish – goldfish, minnows, gambusia [mosquito fish] – to your pond or fountain (or rain barrel). They love noshing on mosquito larvae.
- Put holes in recycling containers so water can escape.
- Eliminate areas on your property where standing water can occur. This may require
- grading,
- fill in dips in the ground,
- plant cattails (an extraordinary plant with a wide variety of uses from converting marsh to dry land, diaper padding, fuel and food)
- Report to the appropriate agency standing water found on county- or state-owned land. This will probably be highway or environment departments.
- Talk to neighbors and/or report standing water on their property, if necessary.
- Make sure water can freely flow through catch basins, storm drains, and uncovered gutters. (Leaves, branches, and trash may clog entries.)
- Frequently inspect outdoor faucets and sprinklers for leaks and fix them promptly.
- Place Bti (Bacillus thuringiensis var. israelensis) in standing water. This bacterium – harmless to fish, birds and mammals but not mosquitoes – is sold as pellets or doughnut-shaped rounds.
DEET and DEET Alternatives
Because of reports of severe, even fatal, reactions and reports of toxicity in fish, DEET (diethyltoluamide, is one of the most commonly found ingredient in products designed to repel a variety of insects including mosquitoes, ticks, and leeches.
Over the years it has been linked to toxicity in animals and recently in humans (which was most likely due to inhaling a product that shouldn’t have been sprayed in the air).
Various agencies emphasize that it must be used according to the label (apply to exposed skin and clothing, wash off during periods it isn’t needed) to avoid complications such as skin irritation, difficulty breathing, burning eyes, headaches, and seizures.
DEET is also a solvent, meaning it can dissolve plastic, rayon, nylon, and other synthetic fabrics as well as varnishes. So it should be handled and stored with care. If you’re among the many who find DEET too high maintenance, the good news is that it’s not the only game in town.
Alternatives to DEET
American beautyberry (Callicarpa), a shrub in the mint family, has four chemicals which have been found to repel insects. The USDA Agriculture Research Service has actually patented one, callicarpenal. The other chemicals are borneol, intermedeol, and spathulenol.
Citronella candles are summer standards found in every type of store. Citronella is the essential oil found in lemongrass, the stalky plant that flavors Thai foods so well. It has been found to be an effective repellant of Asian tiger mosquitoes, leeches, and stable flies. It has been known to increase the heart rate of some people when applied directly to the skin.
Icaridin (hydroxyethyl isobutyl piperidine carboxylate) has been found to be more effective than DEET for repelling certain insects. Also known as picaridin or KBR 3023, Consumer Reports ranked a 20% concentration of the chemical as a top repellant.
Permethrin is a synthetic chemical used to treat a number of conditions and is used by the U.S. military as a defense against ticks and mosquitoes, applied to uniforms and supplies such as tents. Toxic to fish and cats, permethrin is on the World Health Organization’s List of Essential Medicines (the most important medications needed in a basic health system). It is generally applied to mosquito nets and clothing and is also found in flea collars.
Oil of lemon eucalyptus or OLE, is a product of the lemon eucalyptus tree. A natural aging process of the leaves is replicated in the lab, producing a refined oil known as PMD which is known as Citriodiol.
SS220 is a synthetic chemical that has proven to be “significantly better” than DEET at repelling sand flies and mosquitoes. And unlike DEET, it does not cause allergic skin reactions, lasts longer on the skin than other repellents, does not have an oily consistency, and does not tend to plasticize. Its greatest drawback seems to be that it is more expensive to manufacture than DEET or other repellants; which probably explains why it’s not in the ingredients list of any repellants seen to date…
Scents That Mosquitoes Hate
- Catnip, beloved by cats, has been proved to be ten times more effective than DEET in repelling mosquitoes according to the results reported at a conference of the American Chemical Society.
- Basil, lime or sacred, is traditionally held to be an effective repellant among a host of other beneficial uses.
- Rose-scented monarda is said to attract butterflies and bees but repel mosquitoes.
More plants, along with several recipes for skin and other applications, can be found at Auntie Dogma’s Garden Spot. The leaves of these plants must be bruised or crushed to release the oils that produce the scent that drive the mosquitoes away. One easy way to do this is to scatter them on the ground and walk on them. Other strategies are to burn them or make a solution for spraying or applying to skin.
Marigold is that rare plant that has such an objectionable scent just by growing that it repels mosquitoes (and not a few humans). It also protects tomato plants from insects. Unfortunately, its bright leaves attract wasps so you’ll have to find a balance between insects for this to work for you.
A lab in Brazil found coffee to be a useful weapon against mosquitoes. “Day-old caffeine solutions took 20 days to kill 100% of mosquito larvae; 25-day old caffeine solutions killed 100% of mosquito larvae in 1 day.”
A few of these plants are put to use in one DIY repellant recipe from Mother Earth News.
Conspicuous by its absence from the list is the mosquito plant. Although labeled as citronella, it is actually a type of geranium that is marketed in the U.S. and Canada as Pelargonium citrosum or Citrosa geranium. But according to a 1996 study published in the Journal of the American Mosquito Control Association, 1) ‘Pelargonium citrosum’ is not a valid taxonomic designation and 2) research hasn’t found it does much of anything: “Not only was the plant ineffective at protecting humans against Aedes mosquito bites, the mosquitoes were seen landing and resting on the citrosa plant on a regular basis.” [Italics added]
The rain will fall so…
- Take advantage of the free water to water your plants – and if there is a heatwave in July/August, wouldn’t having water stored away come in handy?
- According to the CDC, no cases of Zika have been found in the U.S. since 2017 but it remains something to be aware of when traveling out of the country gets going again.
West Nile Virus and Eastern equine encephalitis virus (EEEV) are more likely to be encountered here in the Mid-Atlantic, courtesy of mosquitoes and birds.
The best strategy for preventing mosquito-borne disease is to avoid getting bitten. Make your yard and home a mosquito-free nursery and enjoy the summer rain.
RESOURCES
Avoid Mosquito Bites. Centers for Disease Control and Prevention. June 7, 2016.
Chikungunya Virus. U. S. Centers for Disease Control and Prevention.
DEET. Wikipedia. June 2016
Dengue Fever. Wikipedia.
Mosquito Repellents That Best Protect Against Zika. Consumer Reports. April 2016.
Mother Nature Wins Again. Beautyberry and the DEET. Vasdani K. Alive.com. Updated July 2008.
West Nile Virus. Symptoms. U. S. Centers for Disease Control and Prevention.
Zika – What Can Be Done. U. S. Centers for Disease Control and Prevention. [PDF]
ABOUT THE AUTHOR
Roxanne Corbin has lived most of her life in the mid-Atlantic. She is a latent artist and wistful-thinking gardener. An information hunter by trade, Roxanne is currently working to transition from the corporate world to managing a research and writing business of her own.
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