Mosquitoes have plauged humanity for millennia. They are part of the fly family, with about 165 species in North America. A female can live up to two weeks and deposit several hundred eggs in her lifetime. Mosquitoes can complete a generation in a week or less. The most common in Nebraska are Aedes (daytime biters), Culex (dusk biters that carry West Nile Virus) and Anopheles.
Besides irritating, mosquitoes have changed the course of history. They’ve contributed to the end of the ancient Roman and Greek civilizations, and halted the advances of the Crusades and Alexander the Great. They prevented early colonization in many areas of the Americas, and caused thousands of deaths during construction of the Panama Canal.
Mosquitoes transmit yellow fever, malaria, and more recently, West Nile Virus (WNV) and Zika Virus. They also can cause encephalitis, or sleeping sickness, in people and horses, and heartworms in dogs.
In the U.S., Nebraska ranks second in WNV deaths; state statistics show 68 WNV deaths from 2002-2016. West Nile Virus is a type of encephalitis affecting people and animals. First detected in Nebraska in 2002, by 2016 Nebraska had 68 West Nile fatalities. Nebraska ranks No. 3 in WNV, No. 2 in WNV deaths and No. 1 for WNV in blood donors, according to figures compiled from the Centers for Disease Control and Prevention.
The primary WNV vector, Culex tarsalis, thrives with irrigation, of which Nebraska has plenty. Infected mosquitoes can also spread the Zika virus. To date the 16 cases of Zika in Nebraska have been travel-related only; the specific Aedes mosquitoes that transmit Zika are extremely rare in Nebraska, so transmission by these mosquitoes will be unlikely.
Reducing Mosquito-Borne Illness
Mosquito prevention is key to reducing mosquito-borne illness. Homeowners can help prevent mosquitos by keeping yards mowed and bushes trimmed. Empty water from even such small containers such as a bottlecap, as after three or four days it can be a suitable breeding ground for mosquitoes.
Mosquitoes breed in still, stagnant waters from wading pools, flower pots, clogged gutters, eaves, bird baths, pails, discarded cans, tires, tree holes, road ditches and low areas. Even tarps covering grills and vehicles can hold water conducive to mosquito breeding.
Nebraska has 50 mosquito species, about half of which bite people. Only female mosquitoes bite, needing blood to produce eggs. Eggs laid on damp soil can hatch immediately after a rainfall – or even years later.
Mosquitoes have a four-stage life cycle: egg, larva (wiggler), pupa (tumbler) and adult.
Mosquito control can be safe and effective at the larval stage. Biological mosquito larvicides include those containing Bti, (Bacillus thuringiensis subspecies israelensis) or methoprene.
A soil bacterium, Bti contains spores that produce toxins so that larvae die when they consume the spores. Methoprene is a hormone that, when eaten, prevents mosquito larvae from becoming adults.
The products come in various forms. Bti, for example, is available as round briquettes or pellets. Used as directed, they can be safe and effective in troughs, ponds and tanks for weeks or even months. Methoprene is available in granules, liquid and fish-shaped briquets.
The Environmental Protection Agency says methoprene is safe for humans and livestock – it also can be used to control flies and fleas – though it is highly toxic to crayfish, shrimp and crabs.
As with all pesticide products, the label is the law. Apply the proper amount: too little, the product will be ineffective; too much and you’re going against the label, and wasting product and money.
Prevent Mosquito Bites
Experts list the following practices and repellents to prevent mosquito bites.
- In the home, use screens on windows and doors.
- Eliminate sources of standing water.
- Avoid areas where mosquitoes are abundant.
- Mosquitoes can bite through tight clothing. Keep mosquitoes from skin by wearing loose, light-colored clothing, long pants, socks, long sleeves and even head nets for areas of high populations.
- Replace outdoor lights with LED or yellow “bug” lights, which attract fewer mosquitoes than incandescent bulbs.
The most effective mosquito repellents are those containing picaridin, oil of lemon eucalyptus and DEET, depending upon concentrations. With any repellent, use sparingly and only for the time needed, using these guidelines:
- Follow safety directions on the label. For example, apply repellents only to exposed skin, not under clothing.
- Do not apply near eyes and mouth; apply sparingly around ears.
- Spray on hands, then apply to face; never spray directly onto the face.
- Avoid using repellents over cuts, wounds or irritated skin.
- Do not use in enclosed areas, near food or flames.
- Do not breathe in mosquito repellents.
- Do not use on animals unless the label allows it.
- Do not apply repellents to children’s hands (children often put their hands in eyes and mouths); apply to your own hands, then put on the child.
- Do not use oil of lemon eucalyptus on children under age 3; or DEET on babies less than 2 months of age.
- Wash children’s skin and clothes with soap and water after coming indoors.
- Keep all repellents out of reach of children.
- Environmental Protection Agency, https://www.epa.gov/insect-repellents/using-insect-repellents-safely-and-effectively
- Consumer Reports, http://www.consumerreports.org/cro/insect-repellent/buying-guide
- Department of Entomology, University of Nebraska–Lincoln http://entomology.unl.edu/urbanent/mosquito.shtml
- Nebraska Department of Health and Human Services, http://dhhs.ne.gov/publichealth/Pages/wnv.aspx, http://dhhs.ne.gov/publichealth/CDC/Pages/ZikaVirus.aspx
- Center for Disease Control and Prevention, https://www.cdc.gov/westnile/resources/pdfs/data/2-West-Nile-virus-disease-cases-reported-to-CDC-by-state_1999-2015_07072016.pdf