Damage from species of Agromyzidae (Diptera) on their plant host(s) is caused mostly by internal larval feeding, but additional damage can arise from female oviposition and feeding punctures, which results in structural damage, the vectoring of viruses and pathogenic fungi, and the exposure of tissue to secondary infection. Many plants of agricultural and ornamental importance are attacked in the field and in glasshouses, and while fly populations are normally kept in check by hymenopterous parasitoids, they sometimes occur in large enough numbers to affect yield and may destroy entire crops. Species affecting crops may be specialists on one host or a larger number of related hosts, but only 16 species in the genera Liriomyza Mik, Phytomyza Fallén and Tropicomyia Spencer are polyphagous, occurring on many hosts in a wide range of families. The threat of these flies is compounded by increasing insecticide resistance and the ease by which polyphagous species can multiply on weeds around growing areas or on alternate crops. All species are also readily spread through trade on their host plant or in soil, causing some species to become globally invasive, with some being of quarantine concern. Since understanding these pests is integral to their control, the objective of the present study is to provide an overview of agromyzid biology, ecology and agricultural importance. Detailed consideration is additionally provided for 26 major pests of special concern. These include eight species of the subfamily Agromyzinae [Agromyza frontella (Rondani); A. megalopsis Hering; A. parvicornis Loew; Melanagromyza sojae (Zehntner), Ophiomyia phaseoli (Tyron), O. simplex (Loew), O. spencerella (Greathead), and Tropicomyia theae (Cotes)] and 18 species of the subfamily Phytomyzinae [Amauromyza flavifrons (Meigen), Liriomyza brassicae (Riley), L. bryoniae (Kaltenbach), L. chinensis (Kato), L. congesta (Becker), L. huidobrensis (Blanchard), L. langei Frick, L. sativae Blanchard, L. strigata (Meigen), L. trifolii (Burgess), Phytobia cambii (Hendel), Phytomyza gymnostomaLoew, P. horticola Goureau, P. ilicicola Loew, P. ilicis Curtis, P. nigra Meigen, P. rufipes Meigen, and P. syngenesiae (Hardy)]. For each of these species, an overview of contemporary knowledge is provided for identification and diagnosis, global distribution, hosts plant(s), host damage, biology, and means of movement and dispersal. To aid in control, early warning systems, and means of field monitoring and management are provided.

The higher classification of the Clusiidae is reviewed, and the family is divided into the subfamilies Clusiodinae, Clusiinae and the new subfamily Sobarocephalinae, all of which are (re)defined. The newly defined Clusiinae includes the genera Phylloclusia Hendel, 1917, Tetrameringia McAlpine, 1960, Amuroclusia Mamaev, 1987, Clusia Haliday, 1838, Paraclusia Czerny, 1903, Alloclusia Hendel, 1917 and Apiochaeta Czerny, 1903. The Sobarocephalinae includes the genera Sobarocephala Czerny, 1903, Procerosoma gen. n., and Chaetoclusia Coquillett, 1904. The new genus Procerosoma is described for two species, Procerosoma alini (Shatalkin) comb. n. from Brazil and P. prominens sp. n. from Mexico. Sobarocephaloides So?s, 1962 is treated as a junior synonym of Sobarocephala, and Chaetoclusia is redefined to include the monotypic genera Chaetoclusiella So?s, 1962, syn. n. and Trichoclusia So?s, 1962, syn. n. Six new species of Chaetoclusia are described (C. centrofasciata sp. n., C. amplipenis sp. n., C. transversa sp. n., C. inbionella sp. n., C. flava sp. n., and C. furva sp. n.). Chaetoclusia bakeri peruana Hennig, 1938 is included as a junior synonym of C. bakeri Coquillett, 1904. The phylogeny of Chaetoclusia is discussed and a key is provided for its 13 species.

Phytomyza impunita sp. n. is described in the subgenus Ptochomyza Hering. This species is known from a single location in the Republic of South Africa, representing the fifth described species in the subgenus, and the second known Ptochomyza to occur outside of the Palaearctic Region, with P. asparagivora (Spencer) known from southern Europe, Pakistan, Ethiopia and Kenya. The new species is described and figured, and discussed in relation to congeners.

Apiochaeta Czerny, 1903, the only genus of Clusiidae endemic to temperate South America, is revised with the description of 16 species from Chile and Argentina. The redefined Apiochaeta includes all former species of Apiochaeta and Alloclusia Hendel, 1917 syn. n., as well as four species described here as new: A. dacryodes sp. n., A. furcillata sp. n., A. lenticula sp. n. and A. mallochi sp. n. Apiochaeta aequalis Malloch, syn. n. is included as a junior synonym of Apiochaeta aterrima Malloch, Alloclusia varia var. claripennis Malloch, syn. n. is included as a junior synonym of Apiochaeta varia (Malloch), comb. nov., and Peratochaetus limbipennis Rondani syn. n. is treated as a junior synonym of Apiochaeta vitticollis (Blanchard), comb. nov.

Sixteen families were studied from the survey presented here, seven of which were new to Georgia. Of the 62 genera identified, 54 represent new country records. Of the 140 recorded species, 111 are new records for Georgia, whereas 10 are new for science and described here for the first time. The most diverse family was Sphaeroceridae with 39 species, followed by Agromyzidae with 27. Of the newly described species, seven belong to Agromyzidae: Liriomyza priapus Lonsdale, sp. nov.; Phytomyza (Napomyza) alata Lonsdale, sp. nov.; Phytomyza (P.) affinoides Lonsdale, sp. nov.; Phytomyza (P.) orphne Lonsdale, sp. nov.; Phytomyza (P.) pilosinomia Lonsdale, sp. nov.; Phytomyza (P.) skia Lonsdale, sp. nov.; Phytomyza (P.) villosus Lonsdale, sp. nov.; and three to Sphaeroceridae: Copromyza pileus Brice, sp. nov.; Gonioneura lagodekhiensis Brice, sp. nov.; and Terrilimosina irwini Brice, sp. nov.

The Liriomyza blechi group is redefined and revised. Twenty-seven species are recognized, 16 of which are described here as new: L. biloba Lonsdale & Eiseman, L. borboros Lonsdale, L. furvunca Lonsdale, L. halomma Lonsdale, L. hyalina Lonsdale, L. orta Lonsdale, L. paspali Lonsdale & Eiseman, L. platypeos Lonsdale, L. pons Lonsdale, L. quadraticaia Lonsdale, L. samara Lonsdale, L. sphaericaia Lonsdale, L. strigiformis Lonsdale, L. telistyla Lonsdale, L. trispicula Lonsdale and L. zophodes Lonsdale. Most species occur in the Neotropics, with a minority extending into, or restricted to the temperate regions of North and South America. All species are (re)described, and a key, illustrations and photographs are provided. Host usage is still largely unknown, with rearing records available for a minority of species. Liriomyza avicenniae is strictly monophagous, known from a single host species (Avicennia germinans (L.) L.). Aside from L. philadelphivora on Philadelphus species (Hydrangeaceae), those taxa for which data are available occur on the dicot Order Lamiales and/or the subfamily Panicoideae (Poaceae). Rearing data are relatively abundant for several species that feed on both of these distant lineages of monocots and dicots in a form of disjunctive oligophagy, indicating a novel pattern of agromyzid host usage that might be more widespread within the group. The Japanese L. philadelphi Sasakawa is discussed.