The Californian species of Liriomyza Mik are revised, including descriptions, illustrations, photographs and a key to species. Sixty-three species are now known to occur in the state, 12 of which are described here as new: L. bispinula, L. conclavis, L. cunicularia, L. merga, L. miserabilis, L. nebulosa, L. parabella, L. phyllodes, L. projecta, L. salpingion, L. tricornis and L. trixivora. Liriomyza virginica Spencer is included as a junior synonym of L. helianthi Spencer, and L. similis Spencer is included as a synonym of L. artemisiae Spencer. Two species are newly recorded in the United States: L. equiseti Meijere, previously known from Canada and Europe, and L. montana Sehgal, previously known from Canada. A number of specimens of L. brassicae (Riley) have been identified as potential new host “races” or species. Morphological characters are provided to diagnose the sister species L. huidobrensis (Blanchard) and L. langei Frick, previously recognizable only on the basis of molecular data. Numerous new state, county and host records are also presented, and hosts are compared for five of the most common North American agricultural pests: L. brassicae, L. huidobrensis, L. langei, L. sativae Blanchard and L. trifolii (Burgess). California contains the highest diversity of Liriomyza known to occur in North America, containing approximately 70% of all described species known from the lower 48 states.

Study of all flies (Diptera) collected for one year from a four-hectare (150 x 266 meter) patch of cloud forest at 1,600 meters above sea level at Zurquí de Moravia, San José Province, Costa Rica (hereafter referred to as Zurquí), revealed an astounding 4,332 species. This amounts to more than half the number of named species of flies for all of Central America. Specimens were collected with two Malaise traps running continuously and with a wide array of supplementary collecting methods for three days of each month. All morphospecies from all 73 families recorded were fully curated by technicians before submission to an international team of 59 taxonomic experts for identification.Overall, a Malaise trap on the forest edge captured 1,988 species or 51% of all collected dipteran taxa (other than of Phoridae, subsampled only from this and one other Malaise trap). A Malaise trap in the forest sampled 906 species. Of other sampling methods, the combination of four other Malaise traps and an intercept trap, aerial/hand collecting, 10 emergence traps, and four CDC light traps added the greatest number of species to our inventory. This complement of sampling methods was an effective combination for retrieving substantial numbers of species of Diptera. Comparison of select sampling methods (considering 3,487 species of non-phorid Diptera) provided further details regarding how many species were sampled by various methods.Comparison of species numbers from each of two permanent Malaise traps from Zurquí with those of single Malaise traps at each of Tapantí and Las Alturas, 40 and 180 km distant from Zurquí respectively, suggested significant species turnover. Comparison of the greater number of species collected in all traps from Zurquí did not markedly change the degree of similarity between the three sites, although the actual number of species shared did increase.Comparisons of the total number of named and unnamed species of Diptera from four hectares at Zurquí is equivalent to 51% of all flies named from Central America, greater than all the named fly fauna of Colombia, equivalent to 14% of named Neotropical species and equal to about 2.7% of all named Diptera worldwide. Clearly the number of species of Diptera in tropical regions has been severely underestimated and the actual number may surpass the number of species of Coleoptera.Various published extrapolations from limited data to estimate total numbers of species of larger taxonomic categories (e.g., Hexapoda, Arthropoda, Eukaryota, etc.) are highly questionable, and certainly will remain uncertain until we have more exhaustive surveys of all and diverse taxa (like Diptera) from multiple tropical sites.Morphological characterization of species in inventories provides identifications placed in the context of taxonomy, phylogeny, form, and ecology. DNA barcoding species is a valuable tool to estimate species numbers but used alone fails to provide a broader context for the species identified.

Estimations of tropical insect diversity generally suffer from lack of known groups or faunas against which extrapolations can be made, and have seriously underestimated the diversity of some taxa. Here we report the intensive inventory of a four-hectare tropical cloud forest in Costa Rica for one year, which yielded 4332 species of Diptera, providing the first verifiable basis for diversity of a major group of insects at a single site in the tropics. In total 73 families were present, all of which were studied to the species level, providing potentially complete coverage of all families of the order likely to be present at the site. Even so, extrapolations based on our data indicate that with further sampling, the actual total for the site could be closer to 8000 species. Efforts to completely sample a site, although resource-intensive and time-consuming, are needed to better ground estimations of world biodiversity based on limited sampling.

We present rearing records of Agromyzidae (Diptera) from five years of collecting throughout the United States. We review host and distribution data, and describe leaf mines, for 93 species, plus 28 others that could not be confidently identified in the absence of male specimens. We report 147 new host species records, including the first rearing records for Agromyza bispinata Spencer, A. diversa Johnson, A. parca Spencer, A. pudica Spencer, A. vockerothi Spencer, Calycomyza michiganensis Steyskal, Ophiomyia congregata (Malloch), and Phytomyza aldrichi Spencer. Phytomyza anemones Hering and (tentatively identified) Cerodontha (Dizygomyza) iraeos (Robineau-Desvoidy) are new to North America; Agromyza albitarsis Meigen, Amauromyza shepherdiae Sehgal, Aulagromyza populicola (Walker), Liriomyza orilliensis Spencer, Phytomyza linnaeae (Griffiths), P. solidaginivora Spencer, and P. solidaginophaga Sehgal are new to the USA. We also present confirmed USA records for Calycomyza menthae Spencer (previous records were based only on leaf mines), Ophiomyia maura (Meigen) (reported from the USA in older literature but deleted from the fauna in the most recent revision (Spencer & Steyskal 1986)), and Phytomyza astotinensis Griffiths and P. thalictrivora Spencer (previously only tentatively recorded from the USA). We provide 111 additional new state records. We describe the following 30 new species: Agromyza fission, A. soka, Melanagromyza palmeri, Ophiomyia euthamiae, O. mimuli, O. parda, Calycomyza artemisivora, C. avira, C. eupatoriphaga, C. vogelmanni, Cerodontha (Dizygomyza) edithae, Cer. (D.) feldmani, Liriomyza ivorcutleri, L. valerianivora, Phytomyza actaeivora, P. aesculi, P. confusa, P. doellingeriae, P. erigeronis, P. hatfieldae, P. hydrophyllivora, P. palmeri, P. palustris, P. sempervirentis, P. tarnwoodensis, P. tigris, P. triangularidis, P. vancouveriella, P. verbenae, and P. ziziae.