Reducing moisture - including flooded areas, standing water, and untreated, stagnant ponds - around your home can make a significant difference in mosquito populations. And an even greater benefit can result if this is done not only in your own yard, but by all your close neighbors as well.
Mosquitoes thrive in moist areas, and in fact, need them to thrive and breed. Their eggs are laid and hatch in or at the edge of standing or slow waters. The larvae then lives in the water until emerging as adults. Even a small amount of water left in a bucket, sandbox toy, bird bath, or planter, or created by pooling water from a leaky hose, can provide breeding ground for hundreds of mosquitoes.
Although mosquitoes can fly up to 40 miles in a day, those that bug you during your outdoor evening relaxation or neighborhood stroll, are most likely to have been produced in the immediate area.
Thus, an essential key to reducing mosquitoes around - and in - your home, is eliminating the source of infestation. Some of the most common sources of standing water, according to Montana State University (MSU), include:
- puddling from watering and irrigation
- areas periodically inundated from stream runoff and snow melt
- ponds and marshy areas
- in hoof holes left by horses, deer, and other animals around watering areas
- rainwater accumulation that stands for 4 or 5 days
- clogged roof gutters
- dripping outdoor faucets and other water leaks
- boats or canoes that have not been drained
- old tires and other water-holding debris.
Of course, many homes and neighborhoods have still or slow-moving water that is desirable and an aesthetic part of the landscaping. In these areas, MSU advises:
- Periodically monitor standing water for larvae ("wigglers"), perhaps once a week, using a long-handled dipper. Mosquito-monitoring tools can be purchased through CENEX dealers. Be aware the larvae are quite sensitive to movement or vibration and quickly drop down from the surface of the water as you approach or try to scoop them into the dipper. A little practice will make it easier.
- If mosquitoes are found, consider a biological control agent called BTI (Bacillus thuringiensis var. israelensis), which will kill immature mosquitoes, black flies and fungus gnats, but is not harmful to humans, pets, or other organisms. Be sure you ask for BTI rather than just BT, which is effective for different insects.
- Another recommended option is aquatic surface films, or mosquito larvicides. These specially formulated oils containing mineral oil with a small amount of spreading agent suffocate the mosquitoes and can be very effective; some are relatively safe for wildlife.
- Using a combination of both BTI and aquatic surface films will be more effective than either product used alone, states MSU.
In addition to eliminating or treating waters to reduce mosquito populations, a number of techniques can be applied around the home to reduce entry. Recommendations include:
- Inspect and repair all windows and doors. Caulk or weather strip any gaps around the frames. Repair any holes in screens; replace or tighten loose-fitting screening.
- Replace standard mercury vapor lights with high pressure sodium vapor or halogen lights. Bulbs that have pink, yellow or orange tints will be least attractive to flying insects in general.
- Although it is common to place lights on exterior walls near doors, it is better to place the light farther away, using pole lights when possible, with the light shining toward the door for safety.
Over-the-counter indoor aerosol foggers and insecticides, even when label for mosquitoes, are not recommended as they seldom provide relief at dosages applied by homeowners.