The August 20th was World Mosquito Day, marking the 1897 discovery by British doctor Sir Ronald Ross that it's the female Anopheles mosquitoes which transmit Malaria.
This finding provided the foundation for scientists across the world to better understand the deadly role of mosquitoes in disease transmission. Our Monday blog post looked at the scientific advancements being made in the global fight for mosquito control. Today we thought we'd look at some methods of natural mosquito control, and investigate whether they are at all effective.
Natural mosquito control?
For those of us lucky enough to live in places where mosquitoes are just extremely annoying rather than actually life-threatening, there is a saying that goes If you think you're too small to make a difference, try spending the night with a mosquito. Whilst I think the purpose of this saying is meant to be inspiring, it really does highlight just how much of an irritation this tiny pest can be, easily ruining a good night's sleep. And let's not start on the vicious cycle of itching if you start scratching the bites ...
As the parent of a young child, I prefer to look for natural control remedies for pest problems in my home first, rather than immediately resorting to a chemical solution. Of course, working for a pest control company I'm well aware that for serious pest infestations, sometimes only a visit from the experts in pest control will do, but as we head towards summer, I wanted to know whether I should be stocking up on those lavender and lemongrass candles. Can they really keep mosquitoes away?
I turned to my old friend Google to answer this question and to try and understand what - if anything - in lemongrass, lavender, citronella etc repels mosquitoes, and if so, why.
Fact or fiction?
First stop, Horticulture: the Art and Science of Smart Gardening which told me that lemongrass contains citronella, a natural oil that repels mosquitoes. They also suggested planting catnip, rosemary and pennyroyal, as these herbs contain other oils that repel mosquitoes. But that didn't answer my question in its entirety: WHY do these natural oils repel mosquitoes?
The National Pesticide Information Center explained that citronella repels mosquitoes by masking scents that mosquitoes are naturally attracted to, which in turn makes it difficult for mosquitoes to locate food. Mosquitoes find their human hosts by sensing the carbon dioxide we breathe out. But when they get close they locate sites for feeding by detecting volatile chemicals given off by human skin. Citronella masks carbon dioxide and lactic acid in humans, two scents that are attractive to mosquitoes.
Further investigating also yielded this fact: lavender oil contains up to 25% linalool. Linalool is a terpenoid alcohol that contributes to its scent. According to the U.S. Environmental Protection Agency, linalool is also an active ingredient in more than a dozen registered products used to control mosquitoes outside.
Studies show that linalool has the same effect on mosquito olfactory receptors as diethyltoluamide (DEET), a chemical used in many conventional mosquito repellents. Another study found geraniol, the active compound in geranium oil, was actually more effective at repelling mosquitoes than linalool or even citronella.
Therefore, although lavender oil does repel mosquitoes, its effectiveness may be enhanced when used in combination with other oils such as geranium. Lavender oil (like all essential oils) should be diluted with a carrier oil before using on the skin to avoid irritation.
Based on the above, I think it's safe to say that these natural plant oils offer some protection against mosquitoes. However, for areas in which mosquito-borne illnesses are present, it's better to be safe than sorry and to rely on a layered approach towards protecting oneself from mosquito bites. The US Centre for Disease Control (CDC) recommends insect repellant be rubbed on any part of the skin that is not covered by clothes, coupled with the taking of antimalarial drugs when travelling through malaria areas.
Additional tips for preventing mosquito bites:
- Wear a long-sleeved shirt, long pants, and a hat when you are outdoors.
- Spray insect repellent on your clothes for extra protection.
- Sleep in a well-screened or air-conditioned room
- Mosquitoes mostly bite at night (dusk until dawn). Sleep under a permethrin-treated mosquito bed net.
- Stay indoors during the times biting mosquitoes are most active (dusk until dawn).
A few additional things you can do around your home to prevent these biting pests:
- Use natural mosquito control products - they do work! Try natural repellents like citronella, lemongrass, peppermint oil, lemon eucalyptus oil, witch hazel, garlic, lavender and vanilla extract.
- Keep windows closed. After dark, keep windows and doors closed or block out the light with curtains.
- Insect screens. Fit fly screens to windows.
- Cover standing water. Cover water butts with well fitting lids to prevent mosquito larvae in the water.
- Eliminate standing water. Do not leave water standing in watering cans etc as this gives mosquitoes a good place to breed.
- Encourage natural predators. If you have a garden pond, think about getting some goldfish as they eat mosquito larvae - providing natural mosquito control.
Whilst prevention is always better than cure, there are occasions when one has to resort to pesticides. There are many D-I-Y and natural mosquito control products available to get rid of mosquitoes in low-risk areas. It is, however, essential to follow the instructions carefully for safe and effective use.
If in doubt, or for frequent recurrences of the problem, call a professional pest control company such as Rentokil.
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