Q: Are mosquitoes really the most dangerous animal on Earth?
A: Mosquitoes cause more human suffering than any other organism — over one million people worldwide die from mosquito-borne diseases every year. Most people succomb to Malaria, but mosquitoes transmit the following diseases as well: Chikungunya, West Nile virus, Zika, several varities of encephalitis, Dengue and Yellow Fever. Many, many more suffer from life long or temporary debilitating effects left after the victim has recovered and the disease is gone. Not only can mosquitoes carry diseases that afflict humans, they also transmit several diseases and parasites that dogs and horses are very susceptible to. These include dog heartworm, West Nile virus (WNV) and Eastern equine encephalitis (EEE). This is why organized mosquito control using a broad spectrum, integrated mosquito management strategy is such an important public health service. Mosquito-borne diseases that have been regarded as third world issues are surfacing in first world countries including the United States. Our modern life, with inexpensive and accessible travel and shipping has brought these two worlds together like never before.
Q: What’s going on with GMO mosquitoes?
A: Researchers have been looking at using genetically modifed mosquitoes to control one species of mosquito (Aedes aegypti) that can transmit Dengue, Chikungunya and Zika. A private company called Oxitec has developed a means of modifying male Aedes aegypti mosquitoes such that after mating with a female, the resulting offspring cannot survive. The modification is known as a lethal gene or self limiting modification, as the modified mosquitoes cannot continue, multiply or replace the existing Aedes aegypti mosquitoes. Trials have been conducted in countries such as Brazil and Panama with promising results. Oxitec claims their strategey is more effective than existing approaches, is safe, sustainable and protects the environment.
Q: How long do mosquitoes live?
A: Adult mosquitoes live anywhere from a few days to a couple of weeks and sometimes as long as a month. Adults that over winter live several months in a state called diapause.
Q: It’s wintertime and the mosquitoes are terrible. What’s going on?
A: Most every year on the warmer days that we often experience in late January and early February, mosquitoes come out of diapause in search of a bloodmeal to sustain them until spring. The species we normally see in our counties is the Anopheles freeborni. In seasons where we have few or light freezes, more of the mosquitoes seem to survive. The mosquitoes awaken from diapause over a period of about 8 to 12 weeks and then after feeding, re-enter diapause until springtime. Localized treatments at individual homes has proven to be largely ineffective. Mosquitoes from adjacent areas filter back in as quickly as 24 hours. Mounting a larger campaign with fogging trucks requires that we would begin spraying after sunset when we have a temperature inversion. In the winter months, mosquitoes quickly retreat to their hiding places as temperatures rapidly cool. This takes them out of the spray target zone. The District will treat in shops where employees work and for planned large gatherings when mosquitoes are present through the winter.
Q: There are fogging trucks spraying through my neighborhood. Isn’t that dangerous for my health?
A: During the mosquito season the District utilizes fogging trucks to help reduce mosquito numbers in our urban and suburban areas. Normally fogging occurs weekly in the town areas of Sutter and Yuba counties after mosquito populations reach a historical threshold. Occasionally fogging trucks are used for specific measures such as a response to disease detection or a localized mosquito hatch. The District chooses materials used to kill mosquitoes based on factors including product safety, efficacy and label compliance issues. Generally, there is no need to relocate during mosquito control spraying. Risks to people and domestic animals from mosquito control products are very low because of the low rates that are used and the insecticides are not very toxic. Although mosquito control pesticides pose minimal risks to human health and the environment, some people may wish to take further action to minimize or avoid exposure.
Each insecticide includes a label which serves as a set of directions for the handling and use of that specific product. Any products that the District uses in neighborhoods must be labeled for use in neighborhoods. In order for this use language to be included on the label, extensive scientific study is required. The U.S. Environmental Protection Agency is the bureau mandated to establish testing objectives, safety targets and efficacy requirements. Insecticide manufacturers must prove to the EPA that acceptable safety levels will be maintained when their product is to be used in neighborhoods or other intended use sites, including scenarios where human exposure could occur. Products under going testing that can not meet the EPA’s requirements will never be registered for use in the environment. Furthermore, the State of California has its own pesticide regulatory agency known as the Department of Pesticide Regulation. This agency again reviews manufacturer’s pesticide use applications and has the power to reject and/or disallow uses previously reviewed and accepted by the U.S. EPA. The California Department of Agriculture is the agency responsible for ensuring that all of the laws governing pesticide application and label directions are followed. The following links will be helpful in addressing further concerns that you may have.
California Department of Pesticide Regulation | Centers for Disease Control and Prevention | Environmental Protection Agency
Q: Why do mosquito bites itch?
A: They itch because people have allergic reactions at the site of the bite. When the female mosquito bites, she injects a small amount of her saliva under your skin to keep your blood from coagulating. Some people seem to be more allergic than others, suffering a little more from the bite.
Q: How can I avoid getting bitten?
A: Most of the mosquitoes you will encounter around the home bite only at dawn and dusk. So limiting your outdoor activity to daytime hours will really help. Also wearing long sleeves and pants will reduce your exposure. Applying insect repellents is very beneficial. Repellants containing the active ingredient DEET are proven most effective. When you are bitten, immediately washing the area with soap and water will reduce the swelling and itching as will the application of a cold, wet towel or an ice cube. Treating the bite with an anti-itch cream will help keep you from scratching which can lead to a secondary infection.
Q: Is it true that only female mosquitoes bite?
A: Yes. Female mosquitoes are equipped with mouthparts designed to penetrate your skin and take a bloodmeal. Males do not have these parts. Females need a bloodmeal to facilitate egg production.
Q: Could I be raising mosquitoes on my own property?
A: It is very possible. All mosquitoes need standing water in order to reproduce. Any source of water 1/2″ deep or greater standing for about one week can lead to mosquito production. Common sources around the home include: tires, buckets, evaporative coolers, roof gutters, ornamental ponds, bird baths, neglected pools and hot tubs and uncovered boats. Check your yard and encourage your neighbors to do the same. Backyard sources can raise the mosquito species that is a primary West Nile virus transmitter. We strongly encourage residents to report neglected and abandonded pools. There is no charge for District staff to come out, inspect or treat a swimming pool.
Q: Do any animals or other insects prey on mosquitoes?
A: Yes. Bats, birds and dragonflies consume flying insects including mosquitoes. Mosquito larvae also have naturally occurring predators. Some fish, aquatic insects and the larvae of some insects prey on mosquito larvae and other aquatic organisms. Many mosquito control districts make use of some of these natural predators.
Q: How do mosquitoes live thru the long, cold winter?
A: Some mosquito species go thru the winter as adults, some as eggs, and some as larva. Adults enter into a kind of hibernation called diapause. Typically they come out of diapause once toward the end of winter for a bloodmeal to sustain them until spring. Eggs remain inactive, not hatching until the warmer spring and summer months. Larva enter into a slow growth, almost no growth, cycle and mature in the spring.
Q: How many kinds of mosquitoes are there?
A: Worldwide there are about 3,000 recognized mosquito species. California harbors 53 species. In our district there are 23 different species.
Q: Are mosquito-hawks effective predators of mosquitoes?
A: What people often call “Mosquito-hawks” or “Mosquito-eaters” are actually (Crane Flies). Crane Flies do not prey on mosquitoes as many people believe. Crane Flies lay their eggs on the soil. After they hatch, their larvae feed on the bases of grasses. As adults, Crane Flies do not feed. They soon die after mating.
Q: Do mosquitoes transmit AIDS?
A: HIV is a disease of the blood that causes AIDS. It disables the body’s immune system, causing those who have the disease to become sick and die from other infections. So it seems logical that a mosquito could pick up this virus from an infected person and transmit it to another person, much like Malaria or Dengue is transmitted. In order to answer this question let’s consider several angles. HIV doesn’t do so well outside of the human body. Inside the mosquito, HIV cannot replicate. The mosquito does not become HIV-infected. Unlike other mosquito-borne diseases, HIV does not have the mechanisms necessary to travel out of the mosquito’s gut. The mosquito digests the blood that it consumes, including the HIV.
Inside the human bloodstream, HIV does not produce high virus particle levels, as do other diseases. About 70 to 80% of HIV-infected persons have undetectable levels of virus particles in their blood. This makes it virtually impossible for a mosquito to pick up a single HIV virus.
Perhaps the most convincing evidence that mosquitoes don’t transmit HIV is the fact that it isn’t happening. No one has ever become HIV-infected from a mosquito bite. As published by the San Francisco Dept. of Public Health, the real numbers on who is contracting AIDS in the United States thru 1999 show that 83% are male. As of 2004 only 0.1% of AIDS cases were in children 13 years of age and younger. If HIV were being transmitted by mosquitoes, the numbers would include many, many more females, elderly and children. Mosquitoes do not discriminate based on gender or age when seeking their next bloodmeal.
Q: I recently had a residual treatment done by one of your crews, but I’m still getting bites. Were my expectations too high?
A: The active ingredients in the treatment you received remain effective against mosquitoes for up to four weeks. But in order to kill the mosquito, the insect must contact a surface that has been treated. For this reason delay washing off or irrigating areas where technicians have applied the residual spray. Mosquitoes moving in from an untreated area will not be affected unless they contact a treated surface. Other ingredients in the treatmentact as a repellant, keeping mosquitoes away. In most cases, a residual treatment will cause a temporary reduction in the mosquitoes flying about your yard and a reduction in the number of mosquitoes entering your home. A residual treatment will not prevent mosquitoes from biting you or protect you from blood-seeking mosquitoes coming from adjacent areas at peak feeding times- dawn and dusk.