Bookmark and Share

Most Important Mosquito Species in Santa Cruz County

Aedes sierrensis (tree hole mosquito) This species breeds in tree holes (rot cavities or depressions in trees which hold water). If near trees and partially filled with organic debris, containers such as tires and buckets may produce these mosquitoes. The eggs hatch when the tree hole or container fills with water. The adults hatch in March and remain in the area until early summer. This mosquito has a short flight range, is an aggressive biter, and is the primary vector of canine heartworm in Santa Cruz County. It is found in any area where suitable tree holes are found.
Aedes squamiger (Winter salt marsh mosquito)This species is produced in the tidal marshes along the coast, primarily near Pajaro Dunes. The eggs are laid on the marsh in the spring and hatch as soon as winter rains fill the marsh. Adults emerge the following spring. Most of the control effort occurs during the winter. Control is by spraying with biorational materials. Many of the marsh sources are ecologically sensitive areas requiring coordination with other agencies. Adults can fly long distances. The adult is a very aggressive biter and is very noticeable to the public.
Aedes washinoi (Woodland pond mosquito)This mosquito is produced in woodland depressions that fill with water and in the Watsonville Slough System. Most aerial applications are undertaken to control this mosquito during the winter months. Eggs are laid on the mud and organic material along the edges of receding water in these areas. Adults are generally present in the early spring, are very aggressive, and may be found in large numbers. Most of control effort on this species is by use of biorational materials and mosquitofish.
Culex erythrothorax (Tule mosquito)This species breeds in tule marshes throughout the District, but especially in the Watsonville Slough system. Larvae overwinter and emerge as adults during the spring and summer months. This species is capable of reaching extremely high numbers, but does not cause considerable nuisance to the public as it is not an aggressive biter and does not venture far from the marsh. Control is undertaken using biorational materials in granular or pellet form when numbers are relatively high in sources close to populated areas.
Culex pipiens (Northern house mosquito)This species causes the largest number of service requests and is generally an urban problem. The adult can be found all year and breeds in storm drains, catch basins, utility vaults, septic tanks, flooded basements, sumps, and in just about any water container found near humans. The adult readily enters homes and bites at night. Because of the type and variety of breeding sources, it can take many hours to locate the cause of a problem. Continual treatment and monitoring of sources is required to maintain control of these mosquitoes. Calls from the public are vital in locating sources.
Culex tarsalis (Encephalitis mosquito)This mosquito is produced in rain pools, marshes, swimming pools, ponds, and other fresh water sources. Although this species does not produce a large number of the District's service requests, it requires a large part of the control effort to prevent the spread of encephalitis in Santa Cruz County. This species feeds primarily on birds and is only moderately aggressive towards man. Culex tarsalis is capable of reaching very high numbers. Control is by application of biorational materials and mosquito fish stocking.
Culiseta incidens (Cool weather mosquito)This mosquito is produced in fishponds, creeks, and containers. Small sources can produce sufficient numbers to cause discomfort in a neighborhood. This mosquito is moderately aggressive, bites in the evening or shade, and is very noticeable because of its large size. It is primarily a problem of urban and suburban areas. Control is by use of biorational larvicides and mosquitofish.
Culiseta inornata (Winter marsh mosquito)Females of this species rest during the summer and become active in the fall after the first rains. Eggs are laid on the surface of rain filled ponds in the fall. Many generations can be produced in one season. This mosquito bites at dusk in the fall and spring and is moderately aggressive, quite large, and may reach very high numbers. It is very noticeable to the public because of its size and activity. This species is generally found close to temporary fresh water sources. Most of the control effort is by using biorational materials.
Culiseta particeps Larvae of this mosquito occur in shaded clear pools containing algae, leaves, and other debris. Overwintering as adult females, this species becomes active during the early spring through fall. Females prefer large mammals and may feed on man in shaded places. This species occurs in shaded drainages from Freedom to the north coast section of Santa Cruz County. Adults can reach high numbers in localized areas and cause problems in some suburban neighborhoods. Like the other members of this genus occuring in this area, it is a large species. Control is through the use of biorational materials and source modification.