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FIGURE 44-47 (44) Adult female small fruit fly (Drosophilidae: Drosophila). (Photograph by R. D. Akre.) (45) Adult crane fly (Tipulidae). (Photograph by Department of Entomology, Michigan State University.) (46) Ventral view of larva of Blephariceridae showing suctorial discs. (47) Adult net-winged midge (Blephariceridae). (Photographs by G. W. Courtney.)

FIGURE 44-47 (44) Adult female small fruit fly (Drosophilidae: Drosophila). (Photograph by R. D. Akre.) (45) Adult crane fly (Tipulidae). (Photograph by Department of Entomology, Michigan State University.) (46) Ventral view of larva of Blephariceridae showing suctorial discs. (47) Adult net-winged midge (Blephariceridae). (Photographs by G. W. Courtney.)

terrestrial habitats. Larvae are significant shredders (Típula, Pedicia) of leaves that enter streams and are predators (Hexatoma, Dicranota) in aquatic habitats. The moist transition zone between aquatic and terrestrial areas supports a distinct assemblage of species (e.g., Erioptera, Ormosia). Terrestrial habitats are home to species that feed on coniferous (Limonia) and deciduous (Epiphragma) rotting logs or decaying organic material (Tipula) and that may even be pestiferous consumers of sod (Tipula). A few species can tolerate high salinity and inhabit the rocky intertidal zones of marine habitats. The adults generally do not feed, although they are frequently mistaken for "giant mosquitoes." A few taxa possess a long proboscis that presumably allows nectar feeding. Large and gangly, adult crane flies are easily taken by vertebrate predators such as birds.

psychodidae Sand flies (Fig. 30), drain flies, and moth flies are typical representatives of this family and contain 2500 species. Adult sand flies (Phlebotomus) are tropical hematophagous (blood-feeding) flies that can transmit leishmaniasis, a disease caused by parasitic protozoa spread by sand-fly bites. However, most psychodids do not bite and are harmless to humans and livestock. Drain flies (Psychoda and Telmatoscopus) and moth flies (Psychoda) resemble tiny moths (about 2—4 mm in length) with hairy, pointed wings. The former have larvae that develop on the rich organic material that builds up in domestic pipes and drains and can be abundant in households and public restrooms. Moth flies have aquatic to semiaquatic larvae that breathe atmospheric oxygen by maintaining contact with the atmosphere using hydrofuge hairs on their posterior spiracles. Eutrophic lakes, marshes, and wastewater treatment plants may produce large numbers of adults. As detritivores, the larvae of moth flies probably are significant nutrient recyclers in lentic ecosystems.

blephariceridae The net-winged midges (300 species) have peculiar larvae (Fig. 46) that use ventral suckers (suctorial disks) to maintain their positions on rocky substrates in torrential streams. A hydraulic, piston-like apparatus gives the larvae the ability to generate suction that allows their suckers to work—even waterfall habitats are occupied by blepharicerid larvae. The mouthparts are positioned ventrally on the head capsule and are specialized for scraping thin algal films off of rocks within fast-flowing environments. Diatoms and other unicellular algae are most often consumed, but fungi and bacteria may also be included in the larval diet. Pupae are also firmly attached to rocks within the flow with permanent suction pads. The adult (Fig. 47) will emerge and maintain a brief grip on the attached pupal skin as the exoskeleton hardens prior to flight. Little deviation from these habits has been documented within the Blephariceridae. Adults are known as net-winged midges because of the finely divided venation of the wings.

FIGURES 48-51 (48) Larva of mosquito (Culicidae: Aedes aegypti). (49) Pupa of mosquito (Culicidae: Anopheles quadrimaculatus). (Photographs by R. W. Merritt.) (50) Adult Ceratopogonidae. (Photograph by G. W. Courtney.) (51) Adult march fly (Bibionidae). (Photograph by Department of Entomology, Michigan State University.)

FIGURES 48-51 (48) Larva of mosquito (Culicidae: Aedes aegypti). (49) Pupa of mosquito (Culicidae: Anopheles quadrimaculatus). (Photographs by R. W. Merritt.) (50) Adult Ceratopogonidae. (Photograph by G. W. Courtney.) (51) Adult march fly (Bibionidae). (Photograph by Department of Entomology, Michigan State University.)

because of their tumbling action that propels them below the surface when disturbed. Emergence occurs quickly at the water surface as the pupal skin breaks to liberate the adult. Although females feed on sugar sources and may take a blood meal for the purpose of egg production, males feed only on nectar and lack bloodsucking proclivities.

ceratopogonidae This family is known as biting midges, punkies, and no-see-ums and contains 5500 species. The adults (Fig. 50) are minute bloodsuckers that swarm around mammalian hosts, including humans (e.g., Culicoides, Lasiohelea). Certain taxa also feed on other invertebrates as ectoparasites, including crane flies, dragonflies, and mantids. The tiny black to gray adults frequently have darkly patterned wings and relatively long antennae. Larvae are encountered in a variety of standing water habitats, including saturated mud and sand, tree holes (Dasyhelea), rain pools, marshes, lakes, and even hot spring algal mats (Bezzia). The genus Leptoconops can be pestiferous and biting adults are encountered at ocean-side beaches. The larval feeding habits of biting midges consist mostly of scavenging and predatory behavior.

culicidae Mosquitoes (3000 species) (Fig. 29) are well-recognized for their roles in disease agent transmission and as pests to humans, livestock, birds, and a variety of other vertebrate hosts. However, adults may emerge in high numbers and provide ample food for avian, bat, and certain predatory invertebrate populations. Mosquitoes exhibit the ability to colonize new aquatic habitats quickly and can survive in confined container habitats. In terms of mosquito control, the ecological importance of the larvae, pupae, and adults is rarely considered. The larvae are mostly filter feeders, but some scrape organic material and algae from solid substrates in standing water habitats. The clearance rate of particles from standing water is impressive and may alter the characteristics, such as turbidity, of the water the insects inhabit. Larval populations are a major component of the neuston, or water-surface inhabitants, and maintain contact with the atmosphere with their spiracles. Larvae (Fig. 48) are known as "wrigglers" because of their frantic swimming action that allows them to dive when threatened; lessening of light intensity by a mere shadow will initiate the wriggling action in some Culex, making them difficult to collect. Some taxa, such as Culex, Culiseta, and Aedes, have their spiracles positioned apically on respiratory siphons; others, such as Anopheles, lack this breathing-tube apparatus. Mansonia and a few other genera possess siphons that are specialized for piercing the roots of wetland plants such as cattails to obtain oxygen and therefore do not need to come to the water surface to breath. The mosquito pupa (Fig. 49) is free-swimming with respiratory trumpets that allow individuals to obtain atmospheric oxygen; pupae are known as "tumblers"

simuliidae Although the general public is often aware of the pest nature of mosquitoes, knowledge of blood feeding by black flies (1500 species) is often restricted to anglers and those who recreate within or near aquatic systems. Like mosquitoes, the larvae play an important role as filter feeders; however, black flies are restricted to flowing water systems. Larval simuliids spin a patch of silken webbing on the surface of riffle rocks and maintain a hold on the webbing with hooks positioned on the posterior abdominal segment. The mouthparts are modified in many species (e.g., Simulium, Prosimulium) and resemble head fans that allow the larvae to capture organic particles, including materials as small as bacteria. Rocky substrates below dam spillways where organic-rich water flows may support tens of thousands of larvae per square meter. Other species are more mobile and scrape or collect food materials from benthic substrates (Gymnopais and Twinnia). The larvae are apneustic (i.e., lack spiracles) and therefore require moving water for cutaneous respiration. Pupae are firmly attached to areas of rocks exposed to current where thoracic pupal respiratory organs (gill-like structures) dangle in a downstream direction, supplementing spiracular respiration (Fig. 8). Most of the pupa is enclosed within a sheath-like cocoon. As in mosquitoes, males have weak mouthparts and may feed on nectar, whereas the females of most species have short probosci and cutting mouthparts for obtaining a blood meal from their vertebrate hosts. The adults are small and grayish black, lack distinct patterns on the wings, and have short antennae (Fig. 28). Some species can swarm in large numbers and are capable of causing shock in domestic animals (e.g., cattle) due to blood loss.

bibionidae March flies (700 species) are named for their early spring appearance in temperate habitats. The stout, dark-colored adults (Fig. 51) feed on flowers; in contrast, the worm-like larvae are general detritivores and can be found in organic soils and compost heaps in abundance. The common genus Bibio overwinters as larvae prior to forming pupae after being exposed to cold temperatures. One predaceous species, Plecia nearctica, was introduced to the southeastern United States to control mosquitoes. Although its impact on mosquitoes is questionable, its impact on human residents is very real. The adults appear for brief periods (about 2 weeks) in such large numbers as to smear automobile windshields and clog radiators. The smashed bodies may even damage a car's paint if not washed off quickly. The adults are known as "love bugs" because males and females are frequently seen flying in copula.

sciaridae These are known as dark-winged fungus gnats (1000 species) because of their small, gnat-like size and smoky grayish-black wings. Sciara is the genus most frequently encountered by people, as the pale, slender larvae develop in a variety of materials, including potting soil used in greenhouses and household planters. In nature, larvae consume the fungus-rich detritus formed under the bark of rotting trees, as well as within the logs themselves. Organicrich compost heaps and mushrooms are also inhabited by sciarid immatures. Although a few taxa are pests (e.g., Pnyxia attacks mushrooms), most species of this common family are harmless.

cecidomyiidae Gall midges and gall gnats are minute flies that are abundant, species-rich (4500 species), and cosmopolitan. More than 1000 species occur in North America alone, and many undescribed species await taxonomic attention. Most species form distinctive galls within which the maggots develop (Fig. 40). Indeed, it is

FIGURES 52-55 (52) Adult deer fly (Tabanidae). (Photograph by R. W. Merritt.) (53) Adult robber fly (Asilidae). (Photograph by R. W. Sites.) (54) Adult bee fly (Bombyliidae). (Photograph by R. D. Akre.) (55) Adult long-legged fly (Dolichopodidae). (Photograph by Department of Entomology, Michigan State University.)

FIGURES 52-55 (52) Adult deer fly (Tabanidae). (Photograph by R. W. Merritt.) (53) Adult robber fly (Asilidae). (Photograph by R. W. Sites.) (54) Adult bee fly (Bombyliidae). (Photograph by R. D. Akre.) (55) Adult long-legged fly (Dolichopodidae). (Photograph by Department of Entomology, Michigan State University.)

frequently easier to determine what species is attacking a plant based on gall morphology rather than adult or larval morphology. Many people are quite familiar with the plants that are affected, such as the damage from maple leaf spot (Rhabdophaga), or the attack of the Hessian fly (Mayetiola destructor), which can be a serious pest of wheat. However, the Cecidomyiidae as a family shows impressive breadth in the plant species it attacks. A few species (e.g., Miastor) exhibit paedogenesis, whereby the larvae reproduce. The "mother larva" produces a number of larvae within her body, which eventually consume the mother and then escape.

Suborder Brachycera tabanidae The horse flies (e.g., Tabanus, Hybomitra) (Fig. 52) and deer flies (Chrysops, Silvius) (Fig. 52) contain 3000 species and are a familiar insect group to people who frequent rural outdoor areas. The adults are rapid fliers; one species was estimated to fly over 150 km per hour! Eggs are normally laid in masses, frequently on vegetation overhanging water or saturated soils. The cryptic larvae are restricted to aquatic and semiaquatic habitats where most species are predators of other invertebrates. The life cycle generally takes about 1 year to complete, whereas some of the larger horse flies require up to 3 years. Although most species inhabit stagnant habitats, some are found at the margins of streams. Females are blood-feeders and may inflict a painful bite. Rather than puncturing a host's skin and sucking blood like mosquitoes, tabanids create a laceration on the host's skin and quickly lap up the pooling blood before retreating. The attack on livestock can be so severe as to reduce milk yields in dairy cattle. Like many other families of biting flies, females use visual cues to locate hosts and also sense plumes of carbon dioxide produced during vertebrate respiration. Horse flies tend to be large (about 10—25 mm) with nearly colorless or smoky wings, whereas deer flies are smaller (around 8 mm) and have yellow or black bodies that support darkly patterned wings. Human disease transmission by Tabanidae (i.e., tularemia, anthrax) is possible, but not significant in North America. However, transmission can be significant in other areas of the world (e.g., Africa).

rhagionidae The snipe flies (500 species) superficially resemble some deer flies, but have a more slender body. Most common in woodlands, snipe flies are often dull yellow to brown (e.g., Rhagio), but the gold-backed snipe fly (Chrysopilus ornatus) of eastern North America has brilliant gold hairs adorning the thorax and abdomen. Most adults are nectar feeders, whereas a few taxa are predators of flying insects. Larval rhagionids tend to be predators of small invertebrates within masses of rotting wood, organic-rich soil, or compost. One genus (Symphoromyia) of western North America has blood-feeding adults that will bite humans in woodland areas.

mydidae The largest adult Diptera are the mydas flies, with 400 species. Some tropical species are over 50 mm. The adults are dark and have red to yellowish coloration on some abdominal segments. Little biological information is available on this family, although the larvae are predators found in decaying logs in woodlands. Pupae occur a few centimeters below the soil, and are adorned with heavy spikes for digging to the surface just prior to adult emergence. The adults are also thought to be predators that specialize in capturing other flying insects, but a fair number of species have vestigial mouthparts. The females of the latter may simply live on the accumulated fatty tissue in the abdomen.

asilidae The robber flies (5500 species) occur in a vast number of terrestrial habitats; most adult activity occurs in areas that are sunny or at least partially sun lit. Adults (Fig. 53) may reach approximately 30 mm in length (e.g., Proctacanthus), whereas others are less than 10 mm in length (e.g., Holocephala). There is great morphological variation in this family among adults, but all species share in common a conspicuously sunken vertex. Adults are predators that are able to take larger prey such as dragonflies, but the selected prey size varies among species. The type of prey, whether stationary, crawling, or flying, is also species-specific among robber flies. The mouthparts contain a stout proboscis that the adult uses to exsanguinate prey species. Some species (e.g., Laphria) mimic bumble bees, which reduces predatory attempts on the adult. Most larvae live in soil or rotting wood where they hunt other insect larvae and nymphs; however, some species are ectoparasitic on Diptera, Coleoptera, Hymenoptera, and Orthoptera immatures. Very few life history studies have been done on the Asilidae.

bombyliidae Bee flies (5000 species) are stout, hairy-bodied flies and, as the name implies, adults are frequently mistaken for hymenopterans because of their bee-like appearance (Fig. 54). Furthermore, the adult behavior often involves hovering at flowers, beelike, and extending a long proboscis to obtain nectar while in flight! Some taxa have bold patterns on the wings (e.g., Anthrax, Exoprosopa) or have the anterior margin of the wing darkened (e.g., Bombylius). Although a widespread family, most species occur in arid areas. The biology of the immature stages remains unknown for most species, but it appears that all species for which the larval feeding habits are known are parasitic on Diptera, Lepidoptera, Hymenoptera, Coleoptera, and Neuroptera larvae or pupae. Many larvae have relatively large, tong-shaped mandibles, presumably suited to aid the parasitic life history. A few bombyliid species consume grasshopper eggs.

dolichopodidae The long-legged flies (5000 species) are small to minute flies that are often brilliant green, blue, or copper colored (Fig. 55). Males have genitalia that are nearly as long as the other abdominal segments combined (e.g., Dolichopus). Adults participate in complex courtship rituals, and males of some species have legs adorned with flattened hair-like scales used as flags to communicate with females during courtship. The family is impressively diverse in its habitat use, as adults can be abundant in freshwater marshes and lake edges, stream margins, woodlands, open fields, and coastal marine areas. Adults appear to be exclusively predaceous. Larvae have been taken from water, damp soil, grass stems, under bark, and other places. Most taxa are predaceous, but a few (e.g., Thrypticus) are phytophagous. One genus (Medetera) has predaceous larvae that feed on bark beetles.

Suborder Cyclorrhapha phoridae This family, also known as humpbacked flies and scuttle flies (3000 species), is another group of flies that exploits a wide range of habitats and exhibits diverse feeding habits. The humpbacked appearance and reduced venation make the adults easy to identify. Many species are consumers of decaying organic matter and can infest household garbage cans on occasion; the females are strongly attracted to the odor of decay. Other species are more unusual, specializing on the consumption of slug eggs (Megaselia) or parasitic on spiders, millipedes, and at least nine insect orders. Some species are currently targeted as potential biocontrol agents of fire ants, a serious pest in the southern United States. One species is known as the coffin fly (Conicera tibialis) because it was reported to maintain many generations on a single human body in the confines of a buried casket.

syrphidae Like the bee flies, flower fly adults (6000 species) resemble Hymenoptera and can mimic bees, bumble bees, hornets, and others (Fig. 56). Syrphids have the ability to hover (thus, they are also known as hover flies), and

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