DR. CHARLES APPERSON
Reproduced from Wing Beats of the AMCA, the official publication of the Florida Mosquito Control Association. Please use the following citation when referring to this article:
Apperson, C. 1991. The black salt marsh mosquito, Aedes taeniorhynchus Wing Beats, Vol. 2(4):9.
The Black Salt Marsh Mosquito, Aedes taeniorhynchus
Importance
The black salt marsh mosquito is a severe biter of man and livestock along the southern coasts from North Carolina to Florida and in the Caribbean. Unchecked populations can have a major economic impact. While capable of transmitting eastern equine encephalitis and St. Louis encephalitis in the laboratory, it is not a major vector of these diseases in nature. It is, however, an important natural vector of dog heartworm and Venezuelan equine encephalitis.
Graphic Distribution
The black salt marsh mosquito is found on the coastal plains from Massachusetts to Texas, in California along the Pacific Coast and in the Caribbean. It is more abundant in the south.
Adult Description
Generally very dark, black in color; bands of white scales across the upper sides of abdominal segments, in the center of the proboscis and five on each leg.
Larval Habitat
This mosquito breeds in the upper regions of grass salt marshes where it is generally associated with spike grass (Distichlis spicata) and salt meadow hay (Spartina patens). In the south, production also occurs in the high marsh associated with mangroves, saltwort (Batis maritima) and glassworts (Salicornia species). It also breeds on dredge disposal islands along the Atlantic Intracoastal Waterway.
Associated Species
The eastern salt marsh mosquito, Aedes sollicitans, is commonly found associated with Ae. taeniorhynchus in grass salt marshes. Anopheles bradleyi, a member of the Anopheles crucians complex, and An. atropos are brackish water species found with A taeniorhynchus.
Oviposition
Each female will lay one or more clutches of 100 to 200 eggs each, generally in a band along a contour line at a specific elevation relative to the high water line in depressions in the upper regions of salt marshes and mangrove swamps.
Larval Behavior
During the mosquito season, a portion of each egg clutch will hatch when flooded. Productive salt marsh sites are flooded at irregular intervals by wind or lunar tides, or heavy rainfall. Bacteria and other microorganisms provide an abundant food supply. in the field, hundreds to thousands of mature larvae often form tightly clustered "balls" which are thought to be associated with feeding, Under optimal conditions, emergence of adults can occur in as little as six days following egg hatch.
Swarming and Mating
About two days after emergence, males are sexually mature and begin to swarm at twilight over the top of bushes or small trees. These swarms usually last no more than 30 minutes. Females are ready to mate when about 12 days old; they mate only once.
Flight and Migration
After mating, females engage in various forms of searching flights. They may make short flights in search of nectar to sustain nonstop migratory flights in search of hosts. Migration is usually unidirectional and upwind. It is usually associated with broods of mosquitoes that number in the millions. Wind speed, direction, landscape topography and the availability of nectar influence migration patterns. Females generally fly 2 to 5 miles; however, wind assisted flights of over 30 miles are known.
Bloodfeeding
Host seeking occurs in the evening and to a lesser extent in the morning. Females do not seek hosts to any great extent during darkness. In daytime, hosts that move near resting females may be attacked. The black salt marsh mosquito will feed on birds as well as mammals. All populations in Florida exhibit some autogeny which refers to an ability of females to develop eggs without taking a bloodmeal.
Overwintering
At northern latitudes, eggs enter diapause in response to decreasing day length and water temperature; breeding can occur year round in the extreme south.