Garden Views: Suggestions to combat mosquitoes


Pools of standing water in our agricultural areas and in our low-lying areas of residential communities from above average rainfall throughout much of Ohio this past spring and early summer has certainly benefitted mosquitoes. Our current above average temperatures will put mosquito development into hyperdrive. This means mosquitoes can develop from eggs to adults in one week or less depending on the species.

Insects, depending on type, have different lifecycles of development. In the case of the mosquito, they undergo a complete lifecycle. This means they undergo four stages of development. The development cycle includes egg, larvae, pupae, and adult. Looking closely at standing water you may discover mosquito wigglers (larvae) and tumblers (pupae) performing their peculiar water ballet en masse. The wigglers are descriptively named because they snap back-and-forth to wiggle through the water. Most mosquito species obtain oxygen through a breathing tube called a “siphon” located at their back end. You can laugh out loud when you are being bitten by a mosquito. Why may you ask? Because as larvae they breathed via their derriere.

World-wide, there are over 3,500 species of mosquitoes with 59 species found in Ohio. Many species do not bite humans or our pets; they feed on plants. In fact, all male mosquitoes feed entirely on plants. It is primarily only the females in the species Aedes, Anopheles, and Mansonia that bite so they can get blood to mature their eggs.

The problem with blood-feeding mosquitoes, other than the itching from their bites, is they can transmit arboviruses (Arthropod-Borne Virus) and other pathogens. Mosquitoes in the genus Anopheles can carry microscopic worm-like parasites belonging to the genus Plasmodium that produce malaria. Mosquitoes belonging to the genera Aedes, Anopheles, and Mansonia can spread the heartworm parasite, Dirofilaria immitis, to dogs, cats, and other mammals.

Thankfully, we do not suffer from malaria mosquitoes in Ohio. However, heartworm is a serious threat to pets, and we do have mosquitoes that carry several arboviruses. In past years, we have had cases of West Nile Virus, La Crosse Virus, and Jamestown Canyon Virus in humans. So, we must remain vigilant.

Many of the more common mosquito species found in Ohio will readily reproduce around or near homes, and these mosquitoes may not stray far from their breeding sites. Mosquito wigglers require some form of moisture to survive. Even temporary standing water will serve the purpose.

Mosquito breeding sites can be revealed by a slow, close inspection around homes. Stagnant pools of water in ditches are an obvious mosquito generator as are outdoor toys, potted plant trays, bird baths, and anything else that collects and holds water. Less obvious are clogged gutters and downspouts or gutters with poor drainage. Cleaning and discarding water in these items will help to reduce mosquito populations.

Larvicidal products are available for controlling mosquitoes where permanent pools of water are part of the landscape, such as aquatic gardens. The products are based on a naturally occurring bacteria: Bacillus thuringiensis var. israelensis (Bti) (e.g., Mosquito Dunks, Mosquito Beater, etc.). These products can be highly effective; however, as with all pesticides, users must read and follow label directions for maximum effect.

Unfortunately, we have little control over all mosquito breeding sites. Several species will readily breed in water held in tree holes. Indeed, the Eastern Treehole Mosquito (Ochlerotatus triseriatus) is so named because it is commonly found in these sites. So, applying mosquito repellents are an important control option.

Mosquitoes are attracted to carbon dioxide exhaled by people, pets, horses, and other large mammals. Dark clothing, as well as certain floral scents in lotions and soaps, also serve as “eat here” signs to mosquitoes.

Insect repellents may provide some relief from mosquito biting. Products containing DEET (N, N-diethyl-meta-toluamide) (e.g., Deep Woods Off, Repel Sportsmen Max, Backwoods Cutter, etc.) have long been a mainstay in mosquito repellency. Research has also shown the products containing picaridin (e.g., Off Clean Feal Insect Repellant, Sawyer Picaridin, Natrapel Picaridin Insect Repellent Wipes, etc.) or oil of lemon eucalyptus (e.g., Cutter Lemon Eucalyptus Insect Repellent, Repel Lemon Eucalyptus Insect Repellent Spray, etc.) are also effective.

Remember that no insect repellent is fool-proof or ever-lasting. They must be used in strict accordance with label directions to achieve the greatest protection from these buzzing bloodsucking menaces.

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