Mosquito Control After a Hurricane

Tips for Mosquito Control After a Hurricane or a Storm – by Janet Bargar, retired Water Quality Agent, revised in 2017 by Christine Kelly-Begazo

Larvae in bottle cap

Mosquitos are notorious for being able to breed in very little water, some even in less than a teaspoon! After a rain event that leaves standing water for more than a few days, you soon will find mosquito larvae wriggling close to the surface. Of the 167 different species of mosquitos that are in the U.S., over 80 of these are found in Florida. Male mosquitos do not bite and actually feed on nectar and plant fluids. Female mosquitos also feed on nectar and plant fluids but they need a blood meal that contain proteins and other nutrients for egg development. Females will lay multiple batches of eggs and usually need a new blood meal for each batch. A female lives 3-6 weeks and can lay thousands of eggs in her lifetime. Eggs are laid directly on the surface of water or in areas that one day will be immersed in water, and it takes approximately 12-15 days for larvae to molt and emerge as an adult mosquito. Mosquitos are not just a nuisance, but dangerous as well given the fact that they can carry diseases such as Chikungunya, Zika, dengue, malaria, West Nile Virus, Encephalitis and others. Although mosquitoes will never be eliminated, there are things that can be done around the home to make it less hospitable for them. Most mosquito species only travel several hundred feet in their lifetime and so mosquitos in the backyard are usually bred within the neighborhood. The following methods include both physical methods and control products.

The first step is to make sure to not give the mosquitos a place to breed and lay eggs. Take a walk around your property and think like a mosquito. Look for areas that a female mosquito would find favorable for laying eggs, such as water that is in a dark, shady, quiet and well-protected area. Make that area as unfavorable as possible by the following steps:

  • Clean debris from rain gutters. The debris allows water to collect in the gutters.
  • Eliminate standing water on and around structures such as flat roofs and air conditioner units. Fix any leaky pipes or faucets and remove any source of dripping water.
  • Get rid of water in potted plant dishes, garbage cans, old tires, gutters, ditches, wheelbarrows, and hollow trees.
  • Change the water in birdbaths, pet bowls and wading pools every 2-3 days.
  • Keep swimming pools and other water features circulating and chlorinated at all times.
  • Clean up fallen vegetation as quickly as possible; keep lawns mowed regularly and weeds under control.
  • Repair torn screens and/or use mosquito netting.

Control Products and Materials
Sometimes physical control methods may not be enough and additional methods need to be incorporated. There are products that can be used to control either larvae or adult mosquitos. Before using any of these products, read and follow label instructions exactly as stated because some chemicals are extremely harmful to aquatic wildlife.

Larvacides:

  •  B.t.i. (Bacillus thuringiensis var. israelensis) is a bacterium that controls mosquito larvae (“wrigglers”) and is not a threat to humans, animals, and plants. B.t.i. is commercially available in many forms (granular, liquid, dunks and bits) and can be found at most garden centers. To be most effective, follow directions on the label of each product. Products will need to be re-applied as wrigglers reappear. This product is only effective against wrigglers (larvae) – it does not kill adults.
  • Spinosad is a natural insecticide made by mixing two compounds produced by special soil bacterial microbes. It is toxic to a wide variety of pest insects but non-toxic to mammals. M
  • Mineral oil can be added to standing water because it forms a thin film on the surface of the water, which causes larvae and pupae to drown. This is a good control method for containers and plants, such as bromeliads, that collect water.
  • Methoprene is an insect growth regulator and can be used in water containing fish. The product prevents larvae from becoming adults. Read the label instructions carefully before applying.

Adulticides: 

  •  Malathion, temephos, and pyrethrins are chemicals commonly used to control mosquito larvae. Before using these chemicals, read the product’s label and hazard statements concerning fish and other aquatic wildlife to determine if these chemicals are right for your situation. Foggers may also be used to provide temporary relief from adult mosquitos. Use them shortly before an outside activity.
  • Sprays. Treat shrubs and the lower branches of trees where mosquitoes may rest. Use sprays registered for flying insects but will not harm plants.

Depending upon the chemical selected, it may be necessary for you to have a Private Applicator pesticide license. For more information about controlling mosquitos, see the Florida Resident’s Guide to Mosquito Control at: http://edis.ifas.ufl.edu/pdffiles/IN/IN104500.pdf