Mosquitos

Class: Diptera
Order: Curculidae
Family: Aedes, Anopheles,
Culex, Culiseta

Identification: So as I sit here scratching my head and thinking about what pest is prevalent out there right now, I realize that I’m scratching my head not out of bewilderment but because it itches! I’ve gotten more bites this year than I have in the past 3 years. Mosquitoes seem much more abundant this year even though its been a drought year. Would you agree? Mosquitoes are true flies and require blood meals to gain sustenance and reproduce. Mosquitoes undergo complete metamorphosis (egg-larva-pupa-adult) and are aquatic insects.

Many of the species of mosquitoes in our area deposit eggs by constructing an egg ‘raft’. These rafts are sent afloat on standing water. Some species will deposit single eggs in wet, saturated soil of flood plains. Larvae are filter feeders and eat microorganisms and organic matter. Larvae breathe by using unique structures called siphon tubes. Once larvae are fully developed, they pupate into ‘tumblers’ or ‘wigglers.’ This stage is familiar to those out there that fly fish; this is a very productive fly pattern. They are called tumblers because of their frantic, tumbling attempts to avoid predators. The final adult stage emerges from the water surface. As adults take flight, they begin to hunt for blood meals. Adult female mosquitoes are the only ones that require blood meals while males enjoy the passive taste of flower nectar; I will go no further in drawing parallels (insert snicker)... Mosquitoes can be predictable in their feeding times and habitats, some species will only feed during sunset and sunrise, while some species will feed during the day in shady areas. Mosquitoes usually aim for your head or ankles or other body regions that are not in your line of sight. Depending on the species, season and temperature, the complete lifecycle may be as short as four days, or as long as one month. This ability to rapidly reproduce under optimal conditions is the reason why some year’s mosquitoes can be horrible.

Management: First of all, pesticides are not a good, reasonable measure for control. Mosquitoes tend to be an area-wide concern when they are a problem and pesticide management of mosquitoes should be left to municipalities. Pesticides used to manage mosquitoes in your yard will be a very temporary fix.

Habitat Management: What should be done in and around your yard is monitoring for standing, stagnant water and mosquito habitats. Look for objects that might be trapping water such as pots, tarps, cans, tires, plastic sheets, buckets and so on. If you have ponds and birdbaths, manage dense vegetation around these to reduce adult hangouts and change the water frequently in your birdbath if you can. Fill in tree holes and stumps with sand (this is prime mosquito habitat).

Mechanical Devices: Bug-zappers do not appear to catch many mosquitoes but are extremely attractive to many beneficial insects - so don’t use them (Ironically, did you know that the inventors of the electric chair and the bug-zapper are from the same family lineage?). Ultra-sonic devices also are not effective for managing mosquitoes. As researchers gain insight into what environmental cues mosquitoes use for locating hosts, I expect to see more devices that produce odors and carbon dioxide baits to trap mosquitoes, such as the Mosquito Magnet (http://www.mosquitomagnet.com/). Thus far, these devices seem rather impractical for our area and probably are only used in severe situations.

Bug Repellants: Multiple repellants are available and I’m sure that you are familiar with many of them. After many rumors, researchers have tested Skin-So-Soft from Avon, this product does work but only offers protection for 30-40 minutes. Repellants with plant extracts generally are not very effective but more research needs to be done on the various products. Citronella does work in repelling mosquitoes and can last for up to two hours. Bite Blocker is a plant-derived product and offers repellency for 3 ½ hours. Permethrin is not a repellant, but is a registered, fast acting pesticide with relatively low mammalian toxicity. Some products combine a repellant and permethrin, BE SURE YOU READ AND FOLLOW THE LABEL. Permethrin should only be applied to clothing and not your skin. Mixed products can provide protection for over eight hours. The most popular and effective repellant is DEET. This product can provide protections for five hours at pretty low concentrations. Time released DEET formulations provide longer protection at lower concentrations. Again, read the label and follow the directions. For casual use in the back yard, 10-30% DEET is about all you need. Historically, DEET has had many queries as to its toxicity. DEET has been used for over forty years and surprisingly has a safe record. Some people can develop irritations and allergies to DEET, so test with a small amount first before you use all over. Children should only use low concentrations, if any (check the label and consult your pediatrician). DEET can be applied to clothes and does not have to be applied directly to the skin to be effective.

Virus Transmission: Mosquitoes have a long proboscis that pierces the skin in order to feed on blood. While doing so, they inject salivary components to keep that blood flowing. This situation where there is an exchange of fluids is perfect for specialized diseases. I use the term specialized because many times the disease organism exists solely for this interaction. What I’m getting at is mosquitoes cannot transmit many of our blood diseases, such as AIDS, effectively. Mosquitoes do transmit encephalitis in our area from time to time but this is much more common in other areas of our country (Once again we are reminded of this paradise we live in called Whatcom County!). A recent disease that has gotten a lot of attention is the West Nile Virus; this disease was first discovered in New York and did cause a few fatalities. Now the WNV has been located in a couple of other states along the East Coast. An intensive survey for infected birds, mammals and humans is underway and you will hear news of this. Washington State is using sentinel birds to monitor for WNV. Would this be a serious problem in our area? I don’t think so. Mosquitoes are not as populous in our regions as they are in other states. But we should be continually monitoring.

For all the mosquito information you’ve ever wanted: http://mosquito.org

For all the West Nile Virus disease information you’ve ever wanted: http://www.cdc.gov/ncidod/dvbid/westnile/index.htm