Aedes aurifer (Coquillett)
by Wayne J. Crans, Rutgers University
Subgenus : Ochlerotatus
Type of Life Cycle : Univoltine Northern Aedes
Typical Habitat : Freshwater Swamp
Larvae Present : Early Spring
Upper: Double (Occasionally one is triple)
Length: As long as head
Tuft: Large, Inserted before middle of shaft
Abdominal Hairs (Segments III-VI) : 2-2-2-1
Comb Scales : Patch
Index: 3.5 - 4.0
Tuft: Large, Multiple
Pecten: 1-3 teeth detached
Precratal tufts: 3-4
Other : 1) Antenna slender beyond insertion point of tuft
2) Antenna very dark toward tip
3) Saddle spiculate along apical margin
GEOGRAPHIC DISTRIBUTION: Aedes aurifer is a mosquito of the northeastern United States and the very southern portion of eastern Canada. Its range extends from the Canadian border south to Maryland, west to the Missouri border and north to the Great Lakes. In New Jersey, the mosquito reaches greatest numbers in the northern half of the state but is locally abundant as far south as Atlantic County. The mosquito has an affinity for bog habitats and isolated populations probably occur in cranberry bogs throughout much of the New Jersey Pine Barrens.
SEASONAL DISTRIBUTION: Aedes aurifer is a spring species with a single generation of larvae that appear in April and pupate in May. The eggs of this species hatch fairly early in spring but development is slow and larvae can be collected for about 6 weeks. Egg hatch is staggered and a day's collection may include specimens from 2nd to 4th instar. Because of the extended egg hatch, there is less of a difference in the status of larval populations in southern vs. northern New Jersey. The adults are generally on the wing by the second week of May. The females probably lay their eggs within the stands of vegetation that serve as refuge for the larvae. The swamp level drops as the season advances stranding the eggs above the water line. The embryos enter obligatory diapause and the eggs do not hatch until a cold factor is encountered. Eggs are inundated the following spring and the single generation hatches very early in the season to complete the cycle.
LARVAL HABITAT: Aedes aurifer is an early season mosquito that appears to be restricted to fresh water swamps and bogs. Records from other states include woodland pools on the list of breeding habitats. The mosquito is never encountered in snow pools in New Jersey and only inhabits woodland pools that intergrade with a freshwater swamp source and have emergent vegetation within their confines. Carex is an indicator plant for this species in the northern counties of New Jersey and the mosquito reaches highest numbers in northern swamps formed by beaver dams. In southern New Jersey the mosquito is common in abandoned cranberry bogs and in acid water bogs that are choked with emergent vegetation. Swampland that produces Ae. abserratus may have Ae. aurifer as well. If the habitat supports Aedes fitchii, there will undoubtedly be numbers of Ae. aurifer. Non-aedine mosquitoes that share habitat with this species include Culiseta morsitans, Anopheles walkeri and Culex territans. Water that produces Ae. aurifer in May will have large populations of Uranotaenia sapphirina in August.
COMMON ASSOCIATE SPECIES: Ae. abserratus, Ae. fitchii, Cs. morsitans, An. walkeri, Cx. territans
LARVAL COLLECTION: Aedes aurifer is a mosquito that has to be hunted in the larval stage. The larvae scatter widely within the swamp and are rarely found close to the upland border. It is best to wade out well within the swamp before you attempt to sample. Aedes aurifer larvae appear to have an affinity for clumps of emergent vegetation. One quick dip near a floating mat is apt to collect a single specimen. Rarely is more than one 4th instar larva of this species taken in a single dip. The species does appear to congregate in the recesses formed by the tussocks of Carex. Dipping, however, quickly disturbs the larvae and lessens the chances of collecting specimens in that area for some time.
LARVAL IDENTIFICATION: Aedes aurifer larvae are easy to recognize in the field. The larvae rest nearly parallel to the surface and take that position in the dipper before the water settles completely. The larvae propel themselves with their mouth brushes and, unlike most species, move in a forward position. The unique dark and light coloration of the antennae give the head a squared-off shape with short projections that look very much like devil horns. No other aedine larva undergoes this behavior and field identification can usually be made through observation with this species. Under the microscope, the partially constricted antennae are unique for an Aedes and the separated pecten teeth are an easy character for confirmation. The apical border of the saddle bears large spicules in this species which become very evident if you look directly down over a white background. When the specimen is positioned correctly, the spines on the edge of the saddle stand out as tiny teeth.
REPRESENTATIVE COLLECTION RECORDS:
Northern New Jersey
Location: Wallkill Refuge, Sussex Co.
Date : April 20
Habitat : Beaver Swamp
Instar : 2nd to 4th
Central New Jersey
Location: Great Swamp National Wildlife Refuge, Morris County
Date : April 25
Habitat : Freshwater Swamp
Instar : 2nd to 4th & Pupae
Southern New Jersey
Location: Dutchtown, Atlantic Co.
Date : May 1
Habitat : Abandoned Cranberry Bog
Instar : 4th & Pupae
IMPORTANCE: Aedes aurifer is a vicious biter but the mosquito rarely flies far from its breeding habitat and never occurs in numbers. Hikers walking the trails within the Great Swamp find this mosquito intolerable in late May but nuisance levels drop quickly. This mosquito's early season distribution, limited numbers and restriction to wooded habitats renders it as a minor pest in New Jersey.