by Wayne J. Crans, Rutgers University
Subgenus: Ochlerotatus
Type of Life Cycle: Univoltine Northern Aedes
Typical Habitat: Acid water bog
Larvae Present: Early Spring
Head Hairs:
Upper: Single (Occasionally double) Stout
Lower : Single, Stout
Antenna:
Length: Shorter than head
Tuft: Inserted just before middle of shaft
Abdominal Hairs (Segments III-VI): 1-1-1-1
Comb Scales: Single row
Siphon:
Index: 3.5 - 4.0
Tuft: 2-4 Hairs
Pecten: 1-3 teeth detached
Anal Segment:
Saddle: Complete ring
Precratal tufts: None
Other: Dorsal brush of anal segment consisting of 4 LONG SINGLE HAIRS (instead of the normal 2 multiple upper tufts and 2 long, lower single hairs)
GEOGRAPHIC DISTRIBUTION: Ae. abserratus is widely distributed in New Jersey with records from nearly all of the counties in the state. The species reaches greatest numbers in the Northern portion of New Jersey but populations can be found in any area that has suitable larval habitat. Aedes abserratus is normally associated with the acid water bogs that are so common in the northwestern sector of the state. Isolated populations, however, can be found throughout the Pine Barrens region of southern New Jersey.
SEASONAL DISTRIBUTION: Ae. abserratus is an early season univoltine species, thus, only one generation is encountered each year. Early instar larvae are frequently found when ice still covers a portion of the larval habitat. Collections have been made as early as February in the southern half of the state. In the more northern counties, a number of snowpool species appear earlier and Ae. abserratus larvae may not be evident until mid-April. Development is slow during the early season and Ae. abserratus larvae tend to concentrate in the colder portions of the larval habitat. Cool habitats slow down larval development and small numbers of larvae may be collected well into the month of May. In northern New Jersey, Ae. abserratus are in the 3rd instar when Ae. communis and Ae. provocans are pupating. In southern New Jersey, Ae. abserratus are slightly behind Ae. grossbecki, one of the earliest univoltine Aedes to appear in pine barrens habitat. Aedes abserratus adults are on the wing before most counties begin their light-trapping season but specimens do appear in light trap collections throughout most of June.
LARVAL HABITAT: The literature describes Ae. abserratus as a woodland pool species but collection records from New Jersey indicate the species is more frequently found in freshwater bogs and marshes. Bogs containing pockets of sphagnum moss often support large populations of Ae. abserratus. The species can also be collected from habitats dominated by cattail, Carex and variety of minor aquatic plant species. When larvae are found in woodland pools, the pools often contain stands of emergent grasses. In the northernmost counties of New Jersey, Ae. abserratus larvae are common in abandoned beaver ponds. In the Pine Barrens region, the species is frequently mixed with Ae. canadensis in cranberry bogs and the reservoir water sources used to flood areas for cranberry culture.
COMMON ASSOCIATE SPECIES: Ae. cinerius, Ae. aurifer, Ae. canadensis
LARVAL COLLECTION: The larvae of Ae. abserratus tend to congregate near clumps of emergent vegetation. As a result, the species is rarely collected in open water and may be missed by casual dipping. Larvae can be collected by placing the dipper close to emergent vegetation and drawing the water from the denser portions of the emergent mat. Proper placement of the dipper draws water from the inner recesses of the emergent cover and propels the larvae into the dipper. Later instar larvae disperse more widely but generally remain close to emergent vegetation. Dipping close to emergent vegetation enhances the collection of this early season species.
LARVAL IDENTIFICATION: Ae. abserratus larvae are relatively easy to separate from associate species collected in the early Spring. As a result, living larvae can be quickly examined under moderate power and saved for rearing purposes if desired. The single head hairs of this species are remarkably stout and stand out as stiff barbs compared to the head hairs found in other species. The single row of large comb scales and separated pecten teeth are easily discerned in living specimens. Although the saddle is completely ringed, confirmation of the character can be difficult when specimens are alive. Living larvae consistently orient themselves with the air tube pointed straight up, and rolling the specimens sufficiently to examine all aspects of the saddle is quite a task. The 4 long caudal hairs of the dorsal brush are especially diagnostic and can be discerned at very low power. Caution should be exercised with this character if the specimens are early instar. Many Aedes larvae lack the dorsal brush in earlier instars and possess caudal hairs that resemble those of Ae. abserratus.
REPRESENTATIVE COLLECTION RECORDS
Northern New Jersey
Location: High Point State Park, Sussex Co.
Date : April 16, 1994
Habitat : Beaver Swamp on Ridge Rd.
Larvae collected from sedge hummocks
Instar : 2nd & 3rd
Southern New Jersey
Location: Warren Grove, Ocean Co.
Date : April 15, 1993
Habitat : Abandoned Cranberry Bog on Rt. 539
Larvae sparse among leatherleaf
Instar : 3rd & 4th
IMPORTANCE: Blood meal tests on wild-caught specimens collected in New Jersey suggest that Ae. abserratus obtains the majority of its blood meals from mammals. The species will readily attack man and can be a severe nuisance after dark. Its early season distribution, affinity for remote wooded habitats and spotty distribution, however, render the mosquito as a minor pest species in New Jersey.