Uranotaenia sapphirina (Osten Sacken)

by Wayne J. Crans, Rutgers University

Subgenus: Uranotaenia

Type of Life Cycle: Culex pipiens Type

Typical Habitat: Permanent and semi-permanent swamps containing stands of emergent grasses and floating vegetation

Larvae Present: Mid summer through early fall

Head Hairs:

Upper: Single, exceptionally stout

Lower : Single, exceptionally stout

Antenna:

Length: Short, about ¼ as long as head

Tuft: Single, small, inserted on basal 1/3 of shaft

Abdominal Hairs (Segments III-VI): Stellate

Comb Scales: Single row located on the distal margin of a sclerotized plate

Siphon:

Index: 3.5 - 4.5

Tuft: Multiple

Pecten: Evenly spaced, not reaching middle of siphon

Anal Segment:

Saddle: Complete ring

Precratal tufts: None

Other: 1) Head is distinctly longer than wide 2) Specimens look very much like an Anopheles larva with an air tube

GEOGRAPHIC DISTRIBUTION: Uranotaenia sapphirina is found from southeastern Canada to Florida along the eastern seaboard of the United States. Its range extends into the central states west to North Dakota and south into Mexico. The mosquito has been recorded from every county in New Jersey and reaches exceptional numbers in areas where suitable larval habitat is present. The largest populations appear to be concentrated in northern Sussex County, the Great Swamp area of Morris County. The species is also locally abundant in some of the swampland habitats on the inner coastal plain in southern New Jersey.

SEASONAL DISTRIBUTION: Uranotaenia sapphirina has a life cycle that is similar to many of the Culex species. The adult females enter hibernation after they have been inseminated in the fall, pass the winter in a state of torpor and emerge in late spring to initiate a multivoltine breeding season. The species lays unique egg rafts that float partially submerged on the water's surface. Larvae are rarely evident until July, but peak sharply during the month of August. Larvae persist in prime breeding habitat into the month of September but decline sharply with the onset of cool weather. The brightly ornamented adults do not fly far from their breeding site but are readily attracted to artificial light. Light traps that are placed near suitable breeding habitat frequently give an overestimation of this species' population density during the summer months.

LARVAL HABITAT: Uranotaenia sapphirina is a mosquito that is almost always associated with permanent and semi-permanent ponds that support rich stands of emergent and floating vegetation. In many areas of New Jersey, Duckweed (Lemma sp.) appears to be an indicator plant. The larvae often congregate in large numbers among the tiny leaves and trailing roots of this floating aquatic plant. Water depth can vary from a few inches to several feet in the swampland utilized by this species. Uranotaenia sapphirina larvae usually avoid shade and are usually found in greatest abundance in sunlit areas of the breeding habitat.

COMMON ASSOCIATE SPECIES: An. quadrimaculatus, Cx. territans, Cq. perturbans

LARVAL COLLECTION: Uranotaenia sapphirina larvae tend to remain close to mats of floating vegetation and sampling is best achieved by dipping directly into stands of emergent grasses where flotsam is present. The larvae sound with any disturbance and it is best to move frequently and sample over a fairly wide area. Because the species oviposits continuously, there is always a cross section of larval instars mixed with pupae. This is an exceptionally small species and late instar larvae are only half the size of most floodwater species. To obtain numbers of 4th instar larvae for reference material, it is advisable to empty the contents of each dip into a bucket and obtain large numbers of specimens rather than transfer larvae to a collection vial individually from the dipper. The contents of the bucket can then be transferred to a bowl or enamel pan and the larger larvae can be sorted out for preservation.

LARVAL IDENTIFICATION: Uranotaenia sapphirina larvae look very much like an Anopheles with an air tube. They possess the long, narrow head that is characteristic of Anopheles larvae and lie almost parallel to the surface in characteristic anopheline fashion. The air tube on Ur. sapphirina quickly separates this species from Anopheles larvae in the dipper but is easily overlooked in the field and may not be apparent until specimens are placed under a microscope. Once under the microscope, the stout, spine-like head hairs are very characteristic. The large sclerotized plate bearing the comb scales on the eighth abdominal segment is an excellent confirming character.

REPRESENTATIVE COLLECTION RECORDS

Northern New Jersey

Location: Hainesville, Sussex Co.

Date : August 21

Habitat : Beaver Swamp off Rt. 206

Instar : 1st - 4th & Pupae

Central New Jersey

Location: Great Swamp National Refuge, Morris Co.

Date :August 17

Habitat : Numerous locations along raised wooden Nature Walks in the swamp

Instar : 1st - 4th & Pupae

Southern New Jersey

Location: New Brooklyn, Camden Co.

Date :September 2

Habitat : Quaking Bog behind Lake

Instar : 1st - 4th & Pupae

IMPORTANCE: Uranotaenia sapphirina is a strikingly beautiful little mosquito with no known medical or economic importance. The tiny adults are liberally sprinkled with iridescent sapphire blue scales making them a welcome sight among the dull brown specimens that normally turn up in most light trap collections. The females are not known to bite humans, cannot be coaxed into feeding on any animals in our laboratories and may be autogenous in nature.

This webpage was begun on 7 July 1996 and last updated on 1 June 2010