Beyond their impacts on our human comfort, mosquitoes pose a serious impact on health through the transmission of diseases to humans and animals. Here in Maricopa County, mosquito-borne encephalitis, aka. sleeping sickness, is of particular concern ... not to mention West Nile. What's more, they aren't just after human blood, but our livestock as well, which can pose critical issues on our own economic welfare. Livestock bothered by these winged foes spend more time scratching and less time eating (time down the drain = money down the drain). When attacked by mosquitoes, our livestock, horses, sheep, and poultry lose weight, which in-turn has its cumulative effect on us. These are reasons enough to take preventive measures both within our individual gardens and yards, as well as our collective urban & rural landscapes.
In order to complete their life cycle ALL mosquitoes require the presence of water. Young mosquitoes hatch and develop in water before maturing into a flying insect. The production of hundreds of thousands of mosquitoes is imminent if larva are allowed to stand in water as little as three days. Hence the rapid increase in populations during the "calm" after the storm. As the rain subsides, our roofs and streets drain and find that low-point in our landscapes or the nearest retention basin. With such large amounts of water inundating the ground all at once, drainage occurs slower and water tends to stagnate. The perfect breeding ground for your pesky friends.
We've come to expect this lil' fella following our June-August showers, and we've learned the stagnant-water lesson the hard way one-to-many times. The most effective method of controlling these tiny insects that pose such a BIG nuisance is targeting them while they are still at the larval stage. Through reduction of potential breeding areas, its is far less likely that they can mature into the adult stage. Outlined below are a handful of ways to address the pest for certain situations.
SPRINKLER & DRIP IRRIGATION
Within our cities, monsoons obviously aren't the only culprit here ... Irrigation water is just as guilty! Most of our urban landscapes, and certainly the majority of our residential neighborhoods today, are irrigated via sprinklers and low-water-use drip systems. Though we often design-for and attempt to manage our water to the lowest-use possible, sometimes our irrigation systems can become a mosquito problem in and of themselves. Luckily, most of the issues we'll encounter can be easily addressed! Here's some of the "biggies" that contribute to excessive, undesired pooling of water in the yard--a surefire waste of water that will increase your personal mosquito habitat!
- Irrigation Timer / Controller: Zone-duration set for too long at turf areas, resulting in a flooded-out lawns. Cut the watering time back!
- Cracked / damaged sprinkler nozzles, OR sprinklers missing entirely (a.k.a. sprinklers-gone-wild / airborne). Fix em'!
- Poor quality drip-irrigation emitters delivering too much water, OR ... too many in one spot. We recommend pressure-compensating emitters so that you are delivering a small amount of water over a longer period of time. This affords the ground time to soak up the water and makes it more readily-available for consumption at your tree / shrub's roots).
- Blown-off flush-caps, missing emitters, or damaged polyethylene drip tubing. For flush-caps that continue to blow off your system, switch it up and install a Figure-8 End Closure. It won't blow off and you'll still have the ability to take it off as desired to flush your lines. Replace your emitters (preferably with pressure compensating emitters) and check for leaks in your drip system often.
- Leaky hose-bibs, spigots, or hoses not completely turned off! If it's-a-leakin', replace it! If it's-a-flowin', turn it off!
For our friends with flood-irrigation, the mosquito has probably become as close as a good family friend! Due to the nature of flooding, you've got a little less control over your water than those with sprinkler-delivered systems. But, we've outlined a couple basic recommendations below to help reduce the chances of your landscape becoming a mosquito palace (for those with sprinkler systems, you might take note on a couple of these for your yard as well).
- Ensure that your land / site is graded properly. If it's a lawn - don't grade pockets into your turf! We're looking for a smooth surface with that low-point out away from the house.
- Consider Core Aerification in spring, summer, or early fall (i.e. break the ground up!) This will reduce compaction, and improve drainage and plant health on sites that have been flood-irrigated for many years. For good results, aerify / aerate with large, half-inch hollow tines, punching about 25 holes/square foot.
- Irrigate only as needed and wet the soil just to the depth of the roots.
- Drain excess water within 24 hours after irrigating (if possible).
- Inspect drainage and broken checks.
- Stay off soft soil, and keep animals off soft soil.
- Avoid over-fertilizing.
Wetlands, ponds, and streams that are well managed and kept clean tend to produce fewer mosquitoes. In nature, these types of waters have plenty of predatory insects or fish (in many cases the water is moving too, not sitting stagnant). If a particular wetland area becomes too shallow or too weedy, mosquito problems persist. This explains why we might experience more mosquitoes off our back porch than out fishing on the lake. Unless predatory insects or fish are introduced, we don't have this natural benefit in our urban landscapes. For urban ponds or locations where ponding cannot be prevented, we recommend the following strategies.
- Chemical Control - Treat the water within 24 to 48 hours with a biologic larvicide. You can introduce a naturally occuring bacterium, such as Bacillus sphaericus (Bs) (VectoLex is the product), which remains active for one to four weeks after application. Bacillus thuringiensis israelensis (Bti) is a naturally occurring soil bacterium that controls mosquito larvae (Look for Aquabac, Bactimos, LarvX, Teknar, or VectoBac). Methroprene is another way to go, which prevents the normal maturation of insect larvae (Look for Altosid, Bayer Advanced Garden Mosquito Preventer, PreStrike, or Zodiac Preventive Mosquito Control). Note: these biologic larvicides are fine to use in livestock troughs too!
- Biological Control - Mosquito Fish to the rescue! The Mosquito Fish (Gambusia affinis) is a small minnow that is a surface-feeder and an effective predator of mosquito larvae. If you've got a pond, this would be a great way to go! In fact the Maricopa County Vector Control office will provide them to you free of charge! Their phone number is (602) 506-0700.
- Remove vegetation, weeds, or floating debris in and around stagnant ponds, ditches, or swimming pools. Vegetation + Water = Breeding Ground. Weeds aren't just water thieves in the garden, they are unsightly and offer the perfect hiding place for mosquitoes! Get them outta' there with the method of your choice: mechanically (pull them) or chemically (spray them). If you are not going to do one of the above, at least keep them trimmed! Remember, the weedier and more shallow a water, the more likely you are to be harvesting your own next mosquito population!
It is not a surprise that the mosquito finds its home in our urban and suburban neighborhoods. They thrive right here beside us because our yards and our homes are often cluttered with all types of "containers". From potted plants, to garden buckets, maybe a bird bath or two ... our landscapes are filled with containers either designed to collect water, OR objects that 'tend' to collect water ... right beneath our noses! Remember, any water that stands for more than 3-4 days is a pest nest! Take a look around to see what 'could' catch water and turn-it over so it drains (if feasible). To prevent a backyard mosquito horde outbreak after the next big rain, consult our mosquito-apocalypse checklist, below! During the monsoons, you'll probably want to drain these items on a weekly basis to play it safe!
- Animal watering troughs (cattle tanks, horse troughs, goat dishes, etc.)
- Pet watering dishes
- Buckets or pool toy containers
- Ruts, containers, plant saucers
- Birdbaths, fountains, or wading/reflecting pools
- Flat roofs (if no drainage system)
- Rain gutters (can accumulate water if built up with debris, inspect on a regular basis)
- Rain barrels / water harvesting catchments / ollas (drain this water into your landscape often, after-all that's what they're for!)
- Industrial / Mechanical areas (old tires, drip pans, equipment)
You might be surprised by how many plants there are that mosquitoes absolutely despise! In most cases, these same plants do double-duty and are useful beyond just keeping the "skeeters" away. Some are edible and have high culinary or medicinal value. What's more, they are all gorgeous plants! Depending upon the season and your space, most of these species would do great in a pot on your porch. Planted in pots, they can be moved around based upon light requirements, where they are needed for repellent most, and they are easier to cover with frost cloth, shade cloth, or bring inside, if desired. Though incorporating plants into your outdoor spaces won't necessarily prevent mosquito larvae from hatching, they will certainly keep the flyers at bay if you're smart with your plantings! Here's the list!
- ARTEMISIA. Aka Wormwood, Yen Chen Hao. Highly aromatic, gray green foliage with a deep sage odor. Used medicinally in Chinese culture. May be difficult to grow in Phoenix, but perhaps northern AZ. Mosquitoes supposedly hate it.
- BASIL. Do up a brew of wicked mosquito repellent with dried leaves, 1/2 cup boiling water, basil essential oil, and 1/2 cup of alcohol! Let it cool, and apply to the skin! Voila! Homemade repellent!
- CATNIP. Your cat will be deliriously happy.
- CITRONELLA. Yes this is a plant, not just a candle. This lemony, grassy plant does great in large containers.
- GARLIC. Who doesn't like garlic? Its amino acid make up converts to a substance called allicin when crushed. Blend up a bunch of garlic, mix into your watering can and hit-up your other patio plants to repel mosquitoes. It's also great in spaghetti sauce!
- GERANIUM. Do up some citronella geraniums in a pot on the patio! Crush the leaves and add to lotions to make a killer homemade repellent!
- LAVENDER. Awesome looking and even more awesome smelling! Mosquitoes hate it!
- LEMON BALM. Better smelling than garlic or citronella. Plant it, crush leaves, and apply directly to skin. Easy as 1...2...3.
- MARIGOLDS. There is a reason gardeners plant marigolds! They work like magic at banishing mosquitoes and other insects!
- PEPPERMINT. Delicious tasting and heavenly smelling! Crush it up and apply to skin. Mosquitoes hate it, but your mojito will love it!
- ROSEMARY. Does awesome here in Phoenix! Smells amazing and great culinary value! Boil 1 cup of dried rosemary in 1 qt. water for 20 minutes. Strain into 1 qt. of filtered water and pour into spray bottles. Bam! You're now armed and dangerous!
Though physically impossible to micro-manage all aspects of our landscapes for pests, including the mighty mosquito, our aim here was to to provide some thoughtful suggestions and commentary on the subject in the hopes of getting us all just a bit closer to a mosquito-free home. With a greater understanding of why mosquitoes are here, and how they miraculously multiply by the thousands, lets all try to do our part to keep em' out! After all, we are ALL responsible for eliminating and preventing mosquito breeding on our own properties (Chapter 11, Regulation 2 of the Maricopa County Health Code). Whatever method you lean toward for control, strive to ensure that it's the most cost effective and environmentally sound option available. Please consider the alternatives that we've outlined above before applying a conventional chemical insecticide.