The Sand Fly
Common Name: Sand Flies, no-see-ums, punkies, biting midges, black gnats Scientific Name: Various Class/Order/Family: Insecta/Diptera/Ceratopogonidae Metamorphosis: Complete
INTRODUCTION
These flies get the common name of sand flies from their being a major pest in coastal areas, that of no-see-ums from the fact that most people do not see them because of their small size, and that of biting midges because of the strong resemblance of some species to midges. These are a pest because of the severe or painful bites they inflict, and they are vectors of disease in livestock. Although found throughout the United States and Canada, they are concentrated along coastal areas and waterways.
RECOGNITION
Adults usually about 1132-118" (1-3 mm; range 1-6 mm) long; slender to moderately robust. Color generally dark, wings sometimes with dark areas. Head with ocelli lacking, eyes touching to widely separated; female with biting and sucking mouthparts. Antennae usually 15-segmented (range 13-15), mate's plumose or featherlik,e. Front tarsi not lengthened. Wing with thickened part of coastal vein (C; on front edge) usually ending 1/2-3/4 way to wing tip, radial veins (R) prominent, medial vein (M) 2-branched, and wings held flat over body at rest.
SIMILAR GROUPS
- Midges (Chironomidae) with thickened part of coastal vein (C) ending near wing tip, medial vein (M) unbranched, front tarsi usually lengthened and wings held rooflike over body at rest.
- Mosquitoes (Culicidae) with scales along veins and wing margin.
- Black flies (Simuliidae) with robust, humpbacked body, antennae short, bare, beadlike segments, and usually 1 1 -segmented (range 9-12).
REPRESENTATIVE SPECIES
- Bodega black gnat, Leptoconops kerteszi Kieffer. Length about 1/16-1/8" (2-3 mm); color black except legs paler towards tarsi and wings white; antenna 15-sagmented in male, 13-sagmented in female; found in western North America, with adults active from early March to early October in California.
- Salt marsh punkie, Cuticoides furens (Posy). Length about 1/16" (2-2.5 mm); color dark with white markings on thorax, wings dark with transparent areas; antenna 15- segmented; found in all Atlantic (Massachusetts southward) and Gulf coastal states in the U.S., with adults active from June into August in New York state.
- Valley black gnat, Leptoconops torrens Townsend. Length about 1/16" (2 mm); color black except legs paler towards tarsi and wings white; antenna 15-segmented in male, 14-segmented in female; found in western U.S., with adults active from mid-May to late June.
BIOLOGY
Eggs are laid in batches varying from 30-40 up to 450. Larvae of Leptoconops burrow in soil, primarily in and areas and on coastal and inland beaches. In some species, they enter diapause as the soil dries out and resume development when the seasonal rains come. Larvae of Culicoides vary in habit from burrowing in moist soil to being fully aquatic and free-swimming. There are 4 larval instars which may require from 3 weeks to 2 years or more in species inhabiting and areas and in some arctic species. The pupal stage is of short duration. Adults of many species assemble in swarms where mating takes place; the male's plumose antennae is an auditory organ which detects the wing beat tone of the female. Females typically require a blood meal before egg laying. Both sexes may visit flowers for nectar. Adults usually live only a few days.
Fortunately in the U.S., sand flies are not known to be disease vectors to humans. However, Cuticoides spp. are vectors of blue tongue virus in sheep and cattle and epizootic hasmorrhagic disease in the Virginian white-tailed deer, Odocoileus virginianus (Zimmermann).
HABITS
Adults typically live in moist areas around the larval habitat. Some species are characteristically found in coastal salt marshes, in inland saline swamps and marshy areas, in heavily fertilized areas frequented by livestock, in cactus, in desert areas, etc.
The density of some species will be reduced to 1/10th at 230 ft (70 m) out from their breeding site. Some species can be blown downwind over 3,281 ft (1,000 m) with no decrease in density indicating that their population density may be more a function of host availability than the distance from the breeding site.
In the more temperate/northern areas, adult sand fly activity begins in the early spring and subsides by late June. The more tropical the area, the longer the adult activity persists to being virtually year round in southern Florida, Texas, and California. Most species of sand flies are crepuscular, active at dusk/sunset. However, most species of Leptoconops are diurnal (active at sunrise and sunset) but some are active in the daytime, while other species are nocturnal.
Both sexes commonly feed on nectar but some males do not feed. Females of most species require a blood meal for egg development. Species of Culicoides, Leptoconops, and some Forcipomyia are bloodsuckers of vertebrates, primarily mammals and birds. Others feed on the blood/haemolymph of large insects such as moths, dragonflies, mayflies, etc.
The mouthparts are somewhat crude compared to mosquitoes. They use a sawlike motion to gain entry through the skin which typically causes a sharp pain and leaves a bright red dot where hemorrhaging has occurred, with a subsequent surrounding inflamed reddish area. Itching can be intense and usually lasts for several days. The intensity of their bite is far far out of proportion to their size and they can be very voracious and persistent feeders.
Many species of adult sand flies assemble in swarms for mating purposes. Such swarms maintain a to-and-fro dancing flight above a landmark such as a bush or pond margin. A few species mate on a substrate, such as the ground, without a swarming flight.