Colorado Master Gardeners: Mosquitos already?

Pests and parasites prominent in summertime such as mosquitoes can carry diseases like West Nile virus.
File photo

Even though we have had a crazy wet, cold, snowy, late spring, the mosquitos are out buzzing our ears and are procreating en masse. You may even see their larvae wiggling in standing water.

Mosquitos spread diseases by biting a disease-infected animal or bird and them moving to another for more food. Zika virus is spread by the Aedes species which doesn’t live in Colorado.

West Nile virus spreads by the mosquitos of the Culex species which feed from the evenings until morning. They carry the virus after feeding on infected birds. The symptoms of a bite from a mosquito with West Nile virus for humans may be mild, but it is best to consult with a health care provider. Horses, however, are in more danger and should be vaccinated by a veterinarian.

First line of defense is to remove all standing water after every rain, including buckets, pots, saucers and bird baths. Check any other standing water frequently for the wiggling larvae.

Also, the mosquitos like dark shrubbery. You could trim them back a bit or use a spray.

There are several ways to protect ourselves from mosquito bites. 

Repellants come in many formulas. The synthetic repellant called DEET is the most studied and used for over 40 years. The plant derived repellants containing citronella and other essential oils are as effective as DEET but must be applied more often. Products containing permethrin as the active ingredient (an insecticide having some repellant properties) may be applied to clothing but not directly to skin.

There are also devices using ultraviolet light, carbon dioxide or an attractant, which are not terribly effective and they also kill a lot of beneficial insects.

For more

Colorado State University Master Gardeners are available to answer questions from 10 a.m. to 1 p.m. Thursdays through the gardening season at the CSU Extension Office, 136 Sixth St. in Steamboat Springs. Contact 970-870-5241 or with questions or to schedule a site visit.

Recommended products to kill the mosquitos can be divided into two main groups: larvicides and adulticides. The first, larvicides, eliminate the larvae before they emerge from the water as adults. These work on bird baths, ponds, water features, stock tanks and areas of standing water. The safest contain Bacillus thuringiensis israelensis known as Bti: Aquabac, Vectobac (which can be mixed in a sprayer), Mosquito Dunks and Mosquito Bits (which can be broadcast). I love the dunks because they are easily found in stores and online. They are safe around pets, children, fish and birds.

Adulticides kill the adult mosquitos. They are not very long-acting but work well before an outdoor function in the evening and in dark shrubbery where the mosquitos will rest between bites. Look for products containing Permethrin: Safer Mosquito control, Raid Yard Guard, Ortho Outdoor Insect Fogger and others.  

More questions may be answered by visiting

The website has a wealth of information as we are thawing out and are in our yards and gardens.

Barbara Sanders has been a Colorado Master Gardener since 1998.

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