Mission Statement: We will minimize mosquito borne Dana Churchel, Program Director COWLITZ COUNTY disease by reducing mosquito Cowlitz County Mosquito Control District MOSQUITO populations in Cowlitz County. CONTROL DISTRICT Policy Statement: It is impossible to eliminate all West Nile virus mosquitoes but by larviciding areas where mosquitoes develop, we can Contingency Plan WORKING TO CONTROL greatly reduce mosquito populations, and thereby reduce the chance of Cowlitz County is ready when WNV is mosquito borne disease. Adult detected. We know our mosquito MOSQUITOES IN mosquito treatments will be made populations. We have equipment Office Location: COWLITZ COUNTY when public health is threatened by and experienced personnel to 1319 South 13th Ave. large populations of mosquito species increase control activities. We also Kelso, WA 98626 that carry disease. have funds if we need other help in our county. Our Priorities: 1. Eliminate or reduce mosquito When WNV is verified: development sites. Mailing Address: 2. Treat areas mosquitoes do develop. PO Box 1261 3. Adulticide public areas, as needed. The Mosquito Control District will: Longview, WA 98632 We will: 1. Place posters in public areas 1. Educate the public telling people how to prevent • how to prevent mosquitoes from mosquito bites Telephone / Fax: developing in their area. 2. Lower our Adulticide trigger (360) 423-5311 • how to reduce mosquito bites. points. 2. Work with the community to identify 3. Increase adult trapping and mosquito breading areas. testing to focus our efforts in Mosquito Hotline: 3. Contact property owners and try to areas where WNV is present. have them clean up or modify their (360) 42 -5658 property so that mosquitoes do not 4. Activate our back up fogger and 5 have a place to develop. increase fogging in areas where 4. Check known development sites and large populations of mosquito treat when larvae are present. that transmit WNv and human 5. Adulticide public areas when adults populations intersect. are present in numbers above our threshold. 5. Treat all catch basins each COWLITZ COUNTY month. HELP US HELP YOU We cannot: 6. Apply barrier treatment in public MOSQUITO 1. Eliminate all mosquitoes from the areas where populations of CONTROL DISTRICT county. mosquito that transmit WNV are FIGHT THE BITE! 2. Remove tires and other debris. above our trigger points. 3. Adulticide private property. Culiseta impatiens CONTROLLING MOSQUITOES IN Found in timbered areas, roadside ditches, Cowlitz Mosquitoes that can carry West Nile virus holes left from fallen or uprooted trees, margins of beaver-dams wheel ruts, and COWLITZ COUNTY other small pools with bordering brush or trees. The fe- THE SCIENCE THE FIELD WORK males will bite man. Aedes japonicus Culiseta inornata Present all season. Larva are typically found in Found in poorly drained irrigated areas and small-volume containers of relatively clean The Cowlitz County Mosquito Control District works The licensed technicians working for Cowlitz from March through September to control mosquitoes in many types of semi permanent and per- water, Also recovered from artificial contain- County Mosquito Control are part-time employees. manent water, also found in shaded pools. ers: bird baths, buckets, plastic milk jugs, wheelbarrows, in the county. With West Nile virus present in adjacent They work evenings and on weekends to apply the The females hibernate, and some larvae may over winter. animal watering containers, and tires and natural containers states, it is only a matter of time before we will be products required for controlling mosquitoes. Should such as tree holes. dealing with mosquitoes, not just as a nuisance, but as West Nile virus come to Cowlitz County, the hours in Ochlerotatus (Aedes) sticticus a public health problem. Aedes vexans the field will increase. Breed in brushy bottom lands along the Columbia River when the Columbia floods. One of the most important pest in flood areas Adults disperse 15 to 20 miles and are a along the Columbia River and its tributaries. serious pest. Eggs remain viable for at least 3 or 4 years Found in partially open, brushy, or wooded Starting in March, licensed The number of adult if not reached by floods. areas. Adults can disperse for 15 to 20 miles. Several hatch- technicians go out into the wetlands mosquitoes is at its peak in July. ings may occur depending on the number of floods. of Cowlitz County, searching for Starting in March, licensed Coquillettidia perturbans mosquito larvae. Dippers are used technicians search for mosquito Anopheles freeborni Eggs are laid in swamps, marshes, or log to scoop up water. The water is larva and apply larvaecide in areas ponds containing cattails, or other suitable Females hibernate in cellars, barns, outbuild- then checked for the presence of where they are present. There are plants. They hatch in 4 or 5 days, and the ings, and sheltered locations. They emerge by several methods of application, but larvae attach themselves to roots or stems of the plants. the last part of February, but few eggs are laid mosquito larvae. The search for It comes to the surface when ready to emerge. They over before April or May. Larvae have been taken along the mar- larvae goes on through September. the most common way is to use a winter in the larval stage. There is one generation each gins of rivers, creeks, and irrigation ditches and in ponds, backpack spreader. This allows the When larvae is found, it is year. The adults readily bite man and animals. sloughs, and roadside ditches. This species can fly as far technician to cover a larger area of as 17.5 miles and live for 3 to 4 months. brought back to the laboratory. larvae infested wetlands While the larvae is still alive, it is Cowlitz Mosquitoes that do not carry West Nile Anopheles punctipennis placed under a microscope to be A licensed technician uses a Usually the species is not sufficiently numer- identified. In 2006, two new species ‘Mozzie’ to treat catch basins with Culiseta incidens ous to be a serious pest. The larvae are often of mosquitoes were discovered in larvaecide. The larvaecide Breed in permanent and semi permanent found in clear shaded pools. Cowlitz County. interferes with the lifecycle of the pools and artificial containers. Only the fe- larvae, preventing it from becoming males hibernate. They will attack man but are not consid- Culex pipiens Two different kinds of traps are an adult mosquito. Most of the ered important because of their small numbers. Develop where humans provide a favorable used to capture adult mosquitoes. products used are species environment. The larvae develop in tempo- The primary trap that is used takes (mosquito) specific. Culiseta particeps rary and permanent pools, catch basins, im- advantage of carbon dioxide (which Found in pools overgrown with vegetation. properly covered cesspools, and artificial containers. The attracts mosquitoes to people) to When the larvae infested area Little is known of the feeding habits of adults. females commonly enter houses and usually bite after dark. bring mosquitoes into a net. These is just too large to be treated by It is probably the most important nocturnal pest of man. Ochlerotatus (Aedes) aborigines traps are usually set out for 12 hand, or with a backpack sprayer, a helicopter is brought in to spread Found in snow and rain pools in wooded and Culex stigmatasoma hours. semi wooded areas. Develop in large numbers in log ponds. They the larvaecide over hundreds of The gravid (egg laying also occur in street catch basins and water acres of wetlands in just a few Ochlerotatus (Aedes) cinereus polluted by sewage. The females rarely bite. mosquitoes) trap uses foul smelling hours. Develop in woodland and open meadow Carbon Dioxide Trap water to attract female mosquitoes. pools. Larvae collected from early April to late Culex tarsalis If there is a particularly large June. The females attack both during the day and at dusk. After the mosquitoes are One of the most important species. Larvae number of adult mosquitoes in an They are known to rest near the ground in the grass or develop in permanent and semi permanent captured, they too are brought back area, a low volume fogger is used underbrush near their breeding sites. water such as log ponds, ditches, and to the lab for identification. If they to spray a fine mist that kills the marshes, also pools formed by floodwaters and irrigation. are known vectors of WNv, they are adult mosquitoes while they are in Ochlerotatus (Aedes) sierrensis Adults seek shelter during the daytime and seldom bite man tested for the presence of the flight. This “fogging” is done from A small mosquito that breeds in tree holes but will attack soon after sundown. Females hibernate in disease. If the test is positive, they dusk to midnight, the hours when and artificial containers, also rock pools and storage cellars, rock piles, and in abandoned mines or are sent to Fort Lewis for the adult mosquitoes are most wooden receptacles under trees and old automobile tires caves. They can disperse 2 and 3 miles in one evening and confirmation. active. and tree stumps. The larvae may be found in midwinter. travel 7 miles or more in two evenings. The life cycle may be completed in as little as 15 days. A Gravid Trap persistent biter but has a restricted flight range. .