These flies are 6-15 mm long and characterized by an enlarged abdomen and short legs; the antennae are slightly longer than

Figure 7.1 Diptera. (a) Syluicola fenestralis wing (Anisopodidae); (b) Dilophusfebrilis, female head (Bibionidae); (c) D.febrilis, male head; (d) Aedesaegypti, female head and thorax (Culicidae); (e) Culicoides sp. (Ceratopogonidae); (f) Chironomus sp. (Chironomidae); (g) Drosophila sp. (Drosophilidae); (h) Musca domestica (Muscidae); (i) Fannia canicu-laris (Muscidae); (j) Megaselia scalaris (Phoridae); (k) Clogmia albipunc-tatus (Psychodidae); (l) Scenopinus sp. (Scenopinidae).

Figure 7.1 Diptera. (a) Syluicola fenestralis wing (Anisopodidae); (b) Dilophusfebrilis, female head (Bibionidae); (c) D.febrilis, male head; (d) Aedesaegypti, female head and thorax (Culicidae); (e) Culicoides sp. (Ceratopogonidae); (f) Chironomus sp. (Chironomidae); (g) Drosophila sp. (Drosophilidae); (h) Musca domestica (Muscidae); (i) Fannia canicu-laris (Muscidae); (j) Megaselia scalaris (Phoridae); (k) Clogmia albipunc-tatus (Psychodidae); (l) Scenopinus sp. (Scenopinidae).

the head, and the eyes are usually large. The body is often covered with fine setae. Some species have color dimorphism: females are often reddish brown, while males are black. Full-grown larvae are 12-24 mm long and nearly cylindrical, and yellowish white with a dark brown head (Fig. 7.2e). There are rows of fleshy processes on the abdominal segments; the spiracles on segment 9 are large. Larvae often feed in large numbers at the roots of grasses, cereals, and in decaying vegetation. Several species are agricultural pests. The urban pest species are Dilophusfebrilis and Bibio marci and B. hortulanus.

After mating, females dig a small cavity in the soil about 5 cm deep with their well-developed tibiae and with the tarsi folded back. A mass of 200-300 eggs is laid in the cavity and the female dies. Hatching occurs in about 30 days and the early-stage larvae often remain together in a mass while feeding. Late-stage larvae have a well-developed head and mandibulate mouthparts. They are 12-segmented and each of the nine abdominal segments has a number of conical processes. There are 10 pairs of spiracles; the spiracles on segment 12 have three openings in Dilophus and two openings in Bibio. Full-grown larvae form chambers in the soil in which to pupate. The pupal period for

Diptera Unter Der Haut
Figure 7.2 Diptera larvae. (a) Chironomus sp. (Chironomidae); (b) Sepsis sp. (Sepsidae); (c) Eristalis sp. (Syrphidae); (d) Scenopinussp., lateral view of the head and anterior segments (Scenopinidae); (e) Bibio sp. (Bibionidae).

most species lasts about 3 weeks and the adults dig their way out of the soil cavity to the surface.

The March fly is Bibio albipennis in North America, and the St. Mark's fly is B. marci in Europe. Both species emerge in large numbers for a few weeks during March and April (April 25 is St. Mark's day); they sometimes create a nuisance around buildings and along roadways. Other bibionids occur in spring, including B. vestitus, Dilophusfebrilis, D. occipitalis, D. ornatus, and the lovebug, or telephone bug, Plecia nearctica. Several of these species have more than one generation per year, and emerge in large numbers in the fall.

March fly, Bibio albipennis Adults are 6-15 mm long; the body is reddish brown and covered with fine setae. The head and eyes are large, and the upper facets ofthe eyes are enlarged in both sexes. Antennae are six- to eight-segmented; the wings have a black spot near the middle of the anterior margin. Adults are weak flyers and are often found on flowers taking nectar. Larvae are cylindrical, legless, and with strong chewing mouthparts; they are often gregarious in moist soil. Eggs are laid on moist or wet vegetation, or directly on the soil surface. Females deposit 200-300 eggs in the few days they are alive; hatching occurs in 2-4 days. Development takes about 14 days; the pupal period is about 10 days. Soil temperature may regulate development time. Adults emerge in the morning and, with increased air temperature, they fly and mate. Swarms consist of males and females seeking mates; mating adults leave the swarm and remain in copula for several hours. This species occurs in the USA.

St. Mark's fly, Bibio marci Adults are 10-12 mm long, with a wing length 8-12 mm. The body is reddish brown to black and covered with fine setae; it is exceptionally long in the male. The thorax is shiny; wings of the male are translucent, while the wings of the female are opaque, both with a darkened costal vein. There is a single large spine on each front tibia. This is the largest bibionid in the UK; adults emerge and swarm in March and April.

Blossom fly, Bibio nervosus Adults are 6-12 mm long and black to reddish black. There are numerous hairs or fine setae on the body, and a black spot near the middle of the anterior edge of the wing. This fly is common on blossoms of fruit trees in the spring in western USA. Large numbers occur on trees around buildings and houses.

Fever fly, Dilophus febrilis (Fig. 7.1 b, c) Adults are about 6 mm long and have a black body and legs, and dark wings. The thorax is shiny, and it is not densely setose in the male. The fore tibia has a single spine placed distant from the main group, and a circle of spines at the tip, and a double ring of spines at the front of the thorax. The wings of the male are translucent and with a distinct stigma; female wings are opaque with pale tips. The male pupa has three pointed processes anteriorly on the head, and a pair of processes at the anterior end; the female pupa has one process anteriorly. Adults have been recorded in large swarms on foliage in residential areas, and they often enter buildings. This species is common throughout the warm months, and there are several generations per year. This species occurs in the UK and perhaps regions of continental Europe. A closely related species, D.femoratus,has 11-segmented antennae and the wings ofmale and female are translucent.

Lovebug, Plecia nearctica Adults are 12-15 long; males are black with black wings, females are black to reddish black, and have dark-gray to black wings. Mating adults remain coupled in flight and this behavior is probably the basis of their common name, lovebug. They emerge in large numbers in April-May, August-September, and sometimes for a brief period in December. Their presence often creates problems with automobile travel and outdoor activities. Adults may be somewhat attracted to automobile exhaust fumes, and gather on or near busy highways. Eggs and body fluids from adult females crushed against car windows are a nuisance and can impair vision. In September 1969, an emergence of P. nearctica in Florida was estimated to extend over 25% of the land area of the state; some adult flies from this emergence were carried by the wind to altitudes of 300-400 m.

Eggs are laid on soil or in wet and decaying vegetation. Females depositabout300 eggs during their lifetime; hatching is in 2-4 days. Development takes about 14 days, and the pupal period is about 7 days. The full-grown larva usually moves away from the breeding substrate to a dry location to pupate. Firstgeneration adults emerge in April and May and the second-generation adults emerge in August and September. The flight period is about 4 weeks, depending on weather conditions. Mating occurs in flight and continues until the male dies or disengages. Males live 2-3 days and females live 7-10 days. P. nearctica was first collected in Florida in 1949. This species is common in all states bordering the Gulf ofMexico, including Georgia and South Carolina, and parts of Central America.

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