Environmental Health Services
Monday - Friday from 8:30 a.m. to 5:00 p.m.
3160 Center Street NE
Salem, OR 97301
Phone: (503) 588-5346
Fax: (503) 566-2986
Facts About Mosquitoes
All mosquitoes must have water in which to complete their life cycle.
Only 7 days are required during warm weather.
Mosquitoes never develop in grass or shrubbery although the flying adults frequently rest there during daylight hours.
Only the female bites to obtain a blood meal. The male mosquito feeds only on plant juices.
The female mosquito may live as long as 3 weeks during the summer and many months during the winter in order to lay her eggs in the spring.
The common mosquito lays a mass of eggs on the water which floats like a raft. Each raft contains from 100 to 400 eggs. The eggs hatch in a day or so into larva.
The larva or "wiggler" comes to the surface to breathe through a tube called a siphon. It sheds its skin or molts four times during the next several days. It grows rapidly between each molt. On the fourth molt it changes into a pupa.
The pupa or "tumbler" cannot eat. It breathes through two tubes on its back. The mosquito grows inside the pupa skin and emerges as an adult to complete the life cycle or metamorphosis of the mosquito.
The newly emerged adult rests on the surface of the water until it is strong enough to fly away for something to eat.
Where To Look & What To Do
Stock with Mosquito Fish. Avoid spraying with garden insect sprays. Remove leaves and thin out pond lilies. Keep water level up. Screen inlet of recirculation pump. Chlorine kills fish - transfer fish to glass bowl when cleaning pond. If pond is no longer desired, break holes in bottom and fill with dirt or sand.
Concrete or Plastic Swimming Pool
Operate filter and skimmer every day to remove egg rafts and larva. Provide drainage for filer and pump sumps. Chlorine will NOT kill mosquito larva. If a pool cover is used, keep it tightly sealed. Remove rain water from top of pool cover. Stock unused or "out-of-order" pools with Mosquito Fish.
Plastic Wading Pools
Change the water every week. Store indoors when on vacation. Store indoors when not in use.
Prevent accumulation of bilge water. Store small boats up-side down or cover to keep out the rain and irrigation water from your sprinklers.
Animal Water Troughs
Stock large troughs with Mosquito Fish. Clean small troughs every week.
Containers Of All Sorts
Remove and dispose of all unused containers that will collect rain water or irrigation water from your sprinklers. Tin Cans, Old Tires, Jars, Buckets, Barrels, Tubs, etc. Home gardener rooting plant cuttings in vases, buckets, etc. should change water every week. Usable containers should be stacked up-side down.
Also look for other standing water under the house. Repair leaking plumbing. Prevent seepage from garden irrigation. Divert storm water away from foundations. Check for standing water in vaults for water softening tank, vaults for house utility meters and at drain outlet from air conditioner.
Gambusia Affinis, called "Mosquito Fish" are non-native predator fish from the eastern and southeastern United States. They eat mosquito larvae as fast as they hatch from the eggs laid by the mosquito in rafts on the surface of the water. They require no feeding and care is limited to protecting them from garden sprays and from chlorine or other chemicals used to clean the pond.
Because Mosquito Fish are non-native fish, state law restricts their use to self-contained waterbodies that are not fed or drained by natural waterways and where no other natural mosquito controls are present.
ODFW - Licensed operators that have fish for sale.
Mosquito Control Resources
AMCA - Mosquito Information
Cornell University - Mosquito Biology for the Homeowner
UC Davis Quick Tips - Mosquitoes
Northwest Mosquito & Vector Control Association
EPA and Mosquito Control
Mosquito Info - Maricopa County, Arizona
Mosquito Control Methods - Rutgers University
CDC Prevent Mosquito Bites
Email Privacy: While we are happy to answer general questions via email, we suggest you do not transmit personal or health related information in your message. We cannot meet any expectation you might have of confidentiality when you communicate with us over the Internet. If you have a specific personal or health-related issue, please call the appropriate county government office instead.
Email address: firstname.lastname@example.org
To report a public health emergency, or make an urgent report of communicable disease, call (503) 588-5621 at anytime.