Mosquito Control: Tactics for the Farm

Let's face it. Unless you are one of the numerous predators that feed on mosquitoes (fish, predacious water beetles, dragonflies, birds and bats to name but a few), you'd probably prefer not to have them around. Swarms of mosquitoes can put a damper on your outdoor activities, requiring you to don protective clothing and use repellents to avoid their annoying, often irritating bites. Fortunately, there are several simple things that you can do to reduce their numbers.

The first step to control mosquitoes on your farm is to identify the potential breeding sites. An understanding of their biology will provide you with some background information on why this is important. Mosquitoes have a four-stage life cycle: egg, larva, pupa and adult. All female mosquitoes lay eggs in or around water. There are many species of mosquitoes and each has its preference for breeding habitats, ranging from clear to grossly polluted water. The main requirement for each is that the water source must be stagnant and relatively undisturbed. The eggs hatch into larvae or "wrigglers" (Figure 1). At the water surface, the larva changes to a pupa before emerging as an adult mosquito. The entire life cycle can be completed in less than 10 days if temperatures are favourable. This is why mosquitoes are able to develop successfully in small containers including pots, bird baths, pools, depressions in the crooks of trees and other "transient" water sources.

Figure 1: (Photo credit: Fiona Hunter)

Potential mosquito breeding sites include any area where there is stagnant water for more than 7 days. Make a map of your farm and mark potential hot spots (just as you would for pest management).

Examples:

• Tire ruts in lane ways
• Tires (including those used to secure tarps; a typical P215/70R15 car tire lying on its side can hold up to one Imperial gallon of shallow, stagnant water up to 1.5 inches deep, with a surface area twice the size of this 8.5" x 11" article, and with a water to tire perimeter length of about 10')
• Containers or drums (including puddles on the lid formed by the lip around the edge of the container)
• Water in catch basins or Hickenbottom drains
• Water in ditches
• Ponds, especially at the edges
• Puddles formed by leaking irrigation pipes
• Water in eaves troughs or rain barrels
• Puddles or ponds of wash water or processing water

Tire ruts in laneways

Old tires

Containers or drums

How to control or eliminate mosquito breeding sites:

• Fill in ruts in lane/grade traffic areas
• Discard old tires (Check your Government Blue Pages under Waste and Recycling for Licensed Landfill Sites, or your Yellow Pages under Recycling Services)
• Drill large holes in tires used to secure tarps so water cannot collect in them, although this can be tricky to do
• Discard unused containers and drums
• Turn containers or drums on their side so they don't collect water
• Clear blocked drains and culverts
• Ensure ditches are not blocked and allow continual flow
• Consider aerating ponds as the movement of the water surface will discourage females from laying their eggs (see Agriculture & Agrifood Canada Infosheet "How to aerate your dugout"
• Mosquitoes prefer to breed in shallow water. By constructing the retention pond with a steep slope and with at least a 60 cm (2 ft) depth mosquitoes are discouraged from using the site for breeding
• Some fish are known to eat mosquito larvae and have been used to keep the number of larvae at a minimum (check with the Ministry of Natural Resources for restrictions prior to releasing fish)
• Clear vegetation from pond edges. Long grasses and weeds along the edge of the pond protect the larvae from potential predators and make it easier for the adult to lay eggs because the area is protected from the wind.
• Prevent organic matter (such as grass or leaves) from entering and accumulating in the pond. This debris supplies the food the larvae need to survive.
• Remove existing organic matter from ponds
• Locate ponds in an open space not sheltered from the wind. The wind may cause movement on the surface of the water that will deter female mosquitoes from laying their eggs at that site
• Keep grass mowed and manage tall weeds to eliminate mosquito resting areas (especially in areas where people are working)
• Prevent leaking irrigation pipes
• Fill problem areas for leaking pipes with gravel to avoid puddles
• Clear leaves and twigs from eaves troughs

Puddle

No puddle

Note that wetlands must not be drained or altered in any way, unless there is an exceptional circumstance of significant human health risk. Consultation with and permission from, the MNR and appropriate Conservation Authority would be required.

For more information see the OMAFRA fact sheet "Controlling Mosquitoes on Horse Farms and Rural Properties"

How many mosquito breeding sites exist in this pile of junk?

Here are just two examples:

Learn more

• How to aerate your dugout
• Controlling Mosquitoes on Horse Farms and Rural Properties

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