Mosquito Treatment

Breeding Sources Controlled

The Southern Nevada Health District controls mosquito breeding sources by stocking mosquito fish and routine larviciding operations throughout the year as necessary. These breeding sources include:

• Irrigation water
• Gutters
• Subdivision drains
• Roadside ditches
• Flood channels
• Ravines
• Public right of ways

The health district works with city, county, state and federal agencies towards permanent correction of these sources.

The Mosquito Life Cycle

• All mosquitoes must have water in which to complete their life cycles.
• Only seven to ten days are required from egg to adult mosquito during warm weather.
• Only female mosquitoes bite. A blood meal is needed to fully develop the eggs. Male mosquitoes feed only on plant juices.
• The female may live three to five weeks during the summer or several months during the winter.

Eggs:

Some mosquitoes lay eggs in a raft containing 100 to 400 eggs, or singly on the water, or on damp ground where water will later cover them.

The eggs hatch in a day or so into larvae.

Larva:

The larva or “wriggler” comes to the surface to breathe through a tube called a siphon. It sheds its skin (molts) four times during the next several days. It grows rapidly between each molt.

On the fourth molt it changes into a pupa.

Pupa:

The pupa or “tumbler” cannot eat. It breathes through tubes on its back. The mosquito grows inside the pupa for about two days, until it is fully developed.

It then splits the pupal skin and emerges as an adult.

Adult:

The newly emerged adult rests on the surface of the water until it is strong enough to fly.

Fish Prevent Mosquitoes

Most fish eat mosquito larvae and are useful in keeping ornamental ponds free of mosquitoes.

Gambusia affinis, called “mosquito fish,” are indispensable to our mosquito control program in Clark County. They eat mosquito larvae as fast as they hatch from the eggs laid by the mosquito.

Mosquito fish are used to stock mosquito breeding sources, such as:

• Ornamental ponds
• Unused or “out-of-order” swimming pools
• Animal water troughs
• Pools of standing water
• Waste water
• Disposal lagoons
• Natural creeks
• Drainage channels

They require no feeding, and care is limited to protecting them from garden sprays and from chlorine or chemicals used to clean the pond.

Mosquito fish do not lay eggs, but give birth to well developed and very active young. They breed throughout the summer and a new brood is produced at intervals of about four to six weeks.

Approximately 100 young are in a single brood, each about one-half inch in total length when born. They are ready to begin the work of destroying mosquito larvae at once.

Gambusia grows rapidly, reaching a maximum size of about two inches. The earliest broods of the season, born in April and May, become sexually mature and produce young when four to five months old.

Larvicide to Control Mosquitoes

Larvicide keeps mosquito larvae from maturing into adults. If the breeding source is not eliminated, larvicide must be re-applied to prevent future breeding.