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Se registra la presencia de cinco especies de Syrphidae en el Campus universitario de la Universidad Nacional de San Antonio Abad del Cusco (UNSAAC), Perú. La colección se realizó empleando red entomológica y aspirador. Las identificaciones se lograron empleando claves especializadas. Lasabundancias de las cinco especies encontradas fueron evaluadas en cuatro sectores del campus. Lasespecies identificadas corresponden a Eupeodes (Metasyrphus) sp., Allograpta sp., Platycheirus(Carposcalis) chalconotus (Philippi, 1865), Toxomerus sp. y Eristalis bogotensis Macquart, 1842.

Studies were conducted to broaden the current knowledge on seasonality, richness, abundance, and role of syrphids flies in the greenhouse pepper agroecosystem (GPA) in northwestern Argentina. In the GPA, a great richness (54 species) and abundance (517 individuals) of syrphids were found within Syrphinae (40 species; 443 individuals) and Eristalinae (14 species; 74 individuals) subfamilies. Besides, three species, Ocyptamus dimidiatus, O. gastrostactus and Toxomerus watsoni, were recorded for the first time in Argentina, and 12 species were recorded for the first time in Tucuman, expanding their geographical distribution to northwestern Argentina. Syrphid population tend to increase in spring and autumn. The environment occupation by different species showed remarkable differences since 41 were found in an open field, three in the greenhouse, and 10 in both environments. The richness and biodiversity were higher at the open field than in the greenhouse, however, these greenhouse species are important as biological control agents (BCA). Among them, the most abundant were Allograpta exotica, A. obliqua, T. duplicatus, Toxomerus sp. 1, O. dimidiatus and O. zoroaster, whose larvae were found feeding on pepper pests such as whiteflies and aphids. New plant-pest-predator associations were established, involving pepper, weeds, aphids, whiteflies, and syrphids. Four collection methods: Malaise trap, sweep net, infested plant tissues, and McPhail trap contributed to 59.2%, 70.4%, 8.6%, and 7.4% of total syrphid richness, respectively. Based on abundance, distribution in the GPA, and direct involvement in pepper pest control, A. exotica, A. obliqua, T. duplicatus, and Toxomerus sp.1 can be used as BCA for the control of whiteflies and aphids in GPA.

Syrphidae, more commonly known as flower flies, are considered one of the most important Diptera families worldwide because of their critical role in pollination, biological control and decomposition of organic matter. The study of these flies in Chile has stagnated due to a lack of local experts as well as the absence of an updated catalog of species. This study is an attempt to remedy the latter of these issues by providing an illustrated and updated catalog to the Syrphidae of Chile. Species are presented under currently accepted names, with synonyms and previous combinations listed and original references. Type localities, world and Chilean distribution by geopolitical Chilean regions, taxonomic and biological notes, a complete record of bibliographic references and extinction risk under IUCN Red List criteria are provided. This catalog recognizes 132 species of Syrphidae, belonging to four subfamilies (Eristalinae, Microdontinae, Pipizinae and Syrphinae), 13 tribes and 47 genera. A total of 46 species (34.84 %) is restricted to the geopolitical territory of Chile. Eight species are considered exotic, one is considered incertae sedis and three are based on doubtful records. Seventeen species of 10 different genera (Copestylum Macquart, 1846; Dolichogyna Macquart, 1842; Eosalpingogaster Hull, 1949b; Eupeodes Osten Sacken, 1877; Meromacrus Rondani, 1848; Palpada Macquart, 1834; Paragus Latreille, 1804; Sphiximorpha Rondani, 1850; Sterphus Philippi, 1865 and Toxomerus Macquart, 1855) are reported from Chile for the first time. A total of 44 species (33.33 %) reported from Chile are directly threatened by human activities such as agriculture, forestry, mining and/or urbanization and indirectly by climate change. The gaps found in the geographic distribution of Chilean flower fly species and what it means for its use by disciplines such as ecology, floral biology and agronomy, are discussed. In addition, the use of this illustrated catalog for biological conservation, the potential definition of priority areas and ecosystem management plans based on this group of Diptera are also discussed.

Syrphid flies (Diptera: Syrphidae) are a cosmopolitan group of flower-visiting insects, though their diversity and importance as pollinators is understudied and often unappreciated. Data on 1,477 Syrphid occurrences and floral associations from three years of pollinator collection (2017-2019) in the Southern Illinois region of Illinois, United States, are here compiled and analyzed. We collected 69 species in 36 genera off of the flowers of 157 plant species. While a richness of 69 species is greater than most other families of flower-visiting insects in our region, a species accumulation curve and regional species pool estimators suggest that at least 33 species are yet uncollected. In order to further the understanding of Syrphidae as pollinators in the Southern Illinois region, we produced a NMDS ordination of floral associations for the most common syrphid species. The NMDS did not sort syrphid species into discrete ecological guilds, and syrphid floral associations generally fit those predicted by traditional pollination syndromes. We also conducted a preliminary analysis of the pollen-carrying capacity of different syrphid taxa, which found severalEristalisspecies to carry pollen loads comparable to the European Honey Bee,Apis mellifera, and showed significant differences in the pollen-carrying capacity of various syrphid species. Notably, the extremely common genusToxomerusand other small Syrphinae species carried very little pollen, while large and pilose Eristalinae species carried large pollen loads.

Resumen. Se documenta por primera vez la presencia de larvas de Toxomerus politus depredando huevos de Spodoptera frugiperda colocados en hojas de maiz en Oaxaca, Mexico.

El pulgón lanígero (Eriosoma lanigerum Hausmann) es un fitófago que incide en huertos de manzano [Malus sylvestris (L.) Mill. var domestica (Borkh) Mansf.] establecidos en el estado de Chihuahua. Para su combate se ha privilegiado el uso de insecticidas convencionales, incurriendo en aplicaciones extemporáneas que posiblemente repercuten en la baja ocurrencia de enemigos naturales. Con base en lo anterior y la reducida información sobre enemigos naturales del pulgón lanígero del manzano en México, durante los años 2011 y 2012 se realizó el presente trabajo con la finalidad de identificar la incidencia de depredadores y parasitoides asociados a colonias de pulgón lanígero en huertos de manzano con diferente manejo de plagas. Por manejo del huerto, se detectaron 38 y 35 ejemplares para los huertos sin manejo y con manejo integrado de plagas, valores que fueron estadísticamente iguales entre sí y diferentes a los 12 ejemplares detectados en el huerto con manejo convencional. Las especies de depredadores asociadas a colonias de pulgón lanígero en Chihuahua fueron: Hippodamia convergens, Chrysopa nigricornis, Chrysopa oculata, Chrysoperla rufilabris, Chrysoperla comanche, Chrysopa spp., Allograpta obliqua, Sirphus sp. y Toxomerus sp., mientras que como parasitoides se detectó solo a Aphelinus mali.

Relatively little is known about pollination and other aspects of the reproductive biology of bamboos, but wind pollination is assumed to be the rule, at least in woody bamboos. Documenting the reproductive biology of woody bamboos is a complex task due to the long periods of time between flowering cycles, which range from 3 to 120 years. Insects visiting Guadua paniculata and G. inermis flowers were collected in the field. Scanning electron micrographs were taken of the visiting insects. Four species of bees, three from tribe Meliponini (Geotrigona acapulconis, Plebeia frontalis and Trigona fulviventris) and one from tribe Apini (Apis mellifera), along with a syrphid fly (Toxomerus teligera) were found visiting bamboo flowers. Some species of Hemiptera were also found feeding on the flowers, such as Neortholomus jamaicensis (Lygaeidae), or preying on the flower visitors (Apiomerus pictipes (Reduviidae)). Insects visiting bamboo inflorescences may facilitate the release of pollen grains into the air, promoting outcrossing and genetic flow among the individuals of the flowering bamboo populations.

The biology and morphology of the larva of Toxomerus pulchellus (Macquart, 1846) are described. The larvae were observed feeding on pollen of seven grasses species in the Lesser Antilles (Martinique, Guadeloupe) and French Guiana. In Martinique, feeding behaviour of adults and larvae on Para grass [ Brachiaria purpurascens (Raddi) Henr.] took place from 5 : 00 to 9 : 00 am. These hours coincide with the period of maximum pollen availability. During the rest of the day and night, larvae stay in the superior leaf sheaths. The larva of T. pulchellus is compared with those larvae of known pollen-feeding species, Toxomerus politus (Say, 1823) and Toxomerus apegiensis (Harbach, 1974). The cephalopharyngeal skeleton of T. pulchellus has features similar to that in T. politus and T. apegiensis., Palynophagie chez la larve de Toxomerus pulchellus (Diptera, Syrphidae). La biologie et la morphologie des larves de Toxomerus pulchellus (Macquart, 1846) sont décrites. Des larves visitant les fleurs de sept espèces de graminées et se nourrissant de leur pollen ont été observées dans les Petites Antilles (Martinique, Guadeloupe) et en Guyane française. En Martinique, l’activité alimentaire des adultes et des larves sur l’herbe de Para [ Brachiaria purpurascens (Raddi) Henr.] a lieu entre 5 h 00 et 9 h 00, coïncidant avec la période durant laquelle un maximum de pollen est disponible. Durant le reste de la journée, les larves restent cachées dans les gaines foliaires supérieures. La larve de T. pulchellus est comparée avec celles des espèces dont l’activité palynophage est connue, Toxomerus politus (Say, 1823) et Toxomerus apegiensis (Harbach, 1974). Le squelette céphalopharyngien de T. pulchellus présente des caractéristiques morphologiques similaires à ceux de T. politus et T. apegiensis., Dumbardon-Martial Eddy. Pollen feeding in the larva of Toxomerus pulchellus (Diptera, Syrphidae). In: Bulletin de la Société entomologique de France, volume 121 (4),2016. pp. 413-420.

The systematics of Ocyptamus sensu lato has been reviewed, its species groups redefined, and some taxa resurrected. These and other related taxa are diagnosed to aid in distinguishing between them. The status of the following genera is revised: Calostigma Shannon stat. rev., Hermesomyia Vockeroth stat. rev., Hybobathus Enderlein stat. rev., Mimocalla Hull stat. rev., Orphnabaccha Hull stat. rev., Pipunculosyrphus Hull stat. rev., Pseudoscaeva Vockeroth stat. rev., and Styxia Hull stat. rev. New species of the Neotropical genus Ocyptamus are described from Costa Rica and Venezuela: Ocyptamus maximus Thompson sp. nov., Ocyptamus myiophagus Thompson sp. nov., and Ocyptamus megafemur Thompson sp. nov. In addition, an identification key for the genera and species groups of Ocyptamus sensu lato is provided, as well as a redescription of Syrphus sargoides Macquart.Lectotypes are designated for Doros disjuncta Sack, Baccha placiva Williston, Baccha pulla Sack, Ocyptamus funebris Macquart, Syrphus sargoides, and Syrphus immaculatus Macquart. Moreover, Syrphus immaculatus Macquart is considered to be a species of the genus Toxomerus, and new species synonyms are also given: Baccha atypica Curran is a junior synonym of Syrphus conjunctus Wiedemann; Baccha flata Hull and Doros disjuncta Sack are jun. syn. of Syrphus sargoides Macquart; Baccha bromleyi Curran is a jun. syn. of Ocyptamus funebris Macquart; Baccha sepia Hull, Baccha danaida Hull, Baccha violacea Hull, and Baccha ursula Hull are all synonyms of Ocyptamus pullus (Sack); Baccha nerissa Hull is a jun. syn. of Pelecinobaccha hiantha (Hull); and Baccha panamensis Curran is a jun. syn. of Pelecinobaccha transatlantica (Schiner).

This study aimed to evaluate the influence of the distance from the edge of native forests on the abundance of aphidophagous hoverflies in wheat fields. The study was conducted in four commercial fields in the North of Paraná State, Brazil, during the wheat crop season of 2009. Two transects were surveyed parallel to the edge of the forest at two distances: 25 (“near”) and 525 meters (“far”) from the edge. The abundance of hoverflies was compared using a χ2 test (p ≤ 0.05). In total, 1,845 hoverflies adults were collected, which represented 15 species and three genera. The most abundant species was Allograpta exotica (60.43%), followed by Toxomerus dispar (17.78%) and Toxomerus watsoni (7.26%) (Diptera: Syrphidae). An important inference was that all fields showed a higher abundance of aphidophagous hoverflies closer to the edge of the forest (25 m) during the wheat tillering stage. The initial abundance of aphidophagous hoverflies in wheat fields is likely greater near the edge because of the availability of resources in the surrounding forest that enhance hoverfly survival during periods of low aphid infestation.

Phylogenetic relationships between two New World Syrphinae taxa (Diptera, Syrphidae), i.e. the highly diverse genus Ocyptamus and the large genus Toxomerus, were analysed based on molecular characters. The monophyly of both taxa was tested and the taxonomic status of included subgenera and species groups was examined. Toxomerus constitutes the monogeneric tribe Toxomerini with more than 140 described species, while Ocyptamus (tribe Syrphini) is a very diverse genus (over 300 spp.) with multiple recognised subgenera and species groups. Sequence data from three gene regions were used: the mitochondrial protein-coding gene cytochrome c oxidase subunit I (COI) and the nuclear 28S and 18S ribosomal RNA genes. The secondary structure of two expansion segments (D2, D3) of the ribosomal 28S RNA gene is presented for the family Syrphidae and used for the first time in a multiple sequence alignment. Molecular data were analysed using parsimony, maximum likelihood and Bayesian inference. Toxomerus was always recovered as monophyletic within Ocyptamus, and relationships to other New World taxa such as Salpingogaster (Eosalpingogaster) were well-supported. Only the subgenera and species groups of Ocyptamus were consistently recovered as monophyletic lineages, thus the apparent non-monophyly of Ocyptamus demands reclassification of this clade.

Toxomerus hauseri Mengual sp. n. and T. picudus Mengual sp. n. are described from Peru and Ecuador respectively. Toxomerus circumcintus (Enderlein, 1938) is treated as a valid species and not considered synonym of T. marginatus, and Toxomerus ovatus (Hull, 1942) is considered junior synonym of Toxomerus nitidus (Schiner, 1868). An identification key for the Toxomerus species with dark abdomens is given along with diagnoses for each studied species.

Resources for natural enemies are often lacking in agricultural fields. The provisioning of floral resources in crop fields can ameliorate this problem by providing nectar and pollen to natural enemies. To select an appropriate floral resource, plants must be screened for their flowering times and attractiveness to natural enemies and pests. We tested the attractiveness of nine species of annual flowering plants to hoverflies, which are important predators of aphids in California lettuce fields. We also sampled arthropods in the foliage of tested plants, to assess the abundances of other natural enemy and pest species that were present. Tested plants included three commonly-used insectary plants and six flowering plant species that showed potential as either harvestable herbs or cut flowers. Harvestable insectary plants may provide additional economic incentive for growers to set aside land for floral resources. The commonly-used insectary plant sweet alyssum consistently attracted the most hoverflies and the least bees, while potentially harvestable plants attracted few hoverflies. Competition with bees may have reduced hoverfly visits to several of the tested plant species. Sweet alyssum also stayed in bloom the longest, and contained the highest numbers of predatory hemipterans. Results suggest that plants should be screened for their attractiveness to not only the target biological control agent, but also to other potential competitors for floral resources. While this initial study focused on a limited selection of harvestable annual plants, a wide variety of other marketable plant species, particularly perennials, remain to be tested for their attractiveness to hoverflies or other beneficial arthropods.

Capturing unusually profitable prey early in life potentially enhances one's future fecundity and survival. Newly emerged crab spiderlings Misumena vatia (Araneae: Thomisidae) occasionally capture prey that greatly exceed them in size. I attempted to evaluate what if any long-term advantage these kills provided by presenting naive, just-emerged spiderlings with syrphid flies Toxomerus marginatus that exceeded the initial mass of the spiderlings six-fold, a prey that the spiderlings occasionally captured in the field. A second group of spiderlings received a single syrphid initially and subsequently a single fruit fly Drosophila melanogaster every other day, and a control group received a fruit fly every other day. The few spiderlings that regularly captured the syrphids gained significantly more mass than the other groups. Individuals taking an initial syrphid and then fruit flies did not gain more mass than controls fed on solely on fruit flies. Neither did a group of spiderlings followed in the...

Jacquemontia species are often found in disturbed areas, and their flowers are ephemeral and very attractive to insects. We investigated the interaction between the flowers of Jacquemontia evolvuloides and its visitors, with emphasis on potential pollinators, considering morphological, temporal, and behavioral aspects, between September/2009 and August/2010 in an anthropized area in Bahia State, Northeastern Brazil. Jacquemontia evolvuloides flowers are diurnal, ephemeral (approximately five to six hours duration), are present throughout the year, and offer nectar and pollen rewards. Because of the floral morphology of J. evolvuloides insect visitors have easy access to its resources, and its pollination could be considered generalized. While J. evolvuloides flowers are visited by several insects, only small bees (Augochlora spp.) and syrphids (Toxomerus spp.) appear to play a role in pollination of flowers. Although bees have been considered efficient pollinators of that plant, the significant presence of syrphids (considered occasional pollinators but showing high frequency visitation), may indicate their role as potential pollinators, especially when bees are not abundant in the fall/winter. As such, even in pollination systems that are considered generalized (with flowers allowing easy access to various visitor groups), visitor size may be an important factor for efficient pollination, especially when associated with high visitation frequencies.

The morphology and biology of the larva of Toxomerus apegiensis (Harbach, 1974) are described from Suriname. This larva feeds on pollen of Olyra obliquifolia Steudel, a bambusoid grass (Poaceae) that grows in the understorey of tropical rainforests. The morphology of the larva of Toxomerus politus (Say, 1823), which feeds on pollen of corn, Zea mays, is redescribed. These species are the only known phytophages within the otherwise predatory genus Toxomerus. The cephalopharyngeal skeleton of T. apegiensis shows features that are hypothesized to be modifications towards pollen feeding. These features are absent in the larva of T. politus. Possible evolutionary scenarios of the development of phytophagy within Toxomerus are briefly discussed based on published information on phylogeny of the genus.

The fall armyworm Spodoptera frugiperda (Smith, 1797) (Lepidoptera: Noctuidae) is one of the most important pests in Brazilian maize fields that causes damage to approximately 57% of the crop (Cruz etal., 1999 S.). However, several biological control agents occur freely in agroecosystems and are known to suppress the S. frugiperda population (Dequech et al., 2004 ; Bortolotto et al., 2014 ). Among the predator insects, hoverflies have been reported to occur in maize fields but are usually associated with aphid infestation (Swaminathanet al., 2015). Thus far, few studies have investigated hoverflies preying on lepidopteran pests, and the spectrum of preys examined is unclear. To our knowledge, this is the first report of Toxomerus dispar larvae (Fabricius, 1794) (Diptera: Syrphidae) preying on S. frugiperda caterpillars (Figure 1).Thirty specimens of hoverfly larvae were collected from 100 plants (in V

Recently (2013-2014), several hoverfly specimens from two localities in Benin and Cameroon (West and Central Africa) were caught from a species that we could not identify using existing identification keys for Afrotropical Syrphidae. Specific identification as Toxomerus floralis (Fabricius) was accomplished using morphology and various Neotropical identification keys. Corroboration of this identification was made by sequencing of the standard COI barcode region and a subsequent BLAST-IDS in BOLD that revealed a 100% sequence similarity with Toxomerus floralis from Suriname (South America). Species identification was further supported by sequencing parts of the nuclear 18S and 28S rRNA genes. The species is widespread in Togo, Benin, Nigeria and Cameroon, and eggs, larvae and adults are abundant at several localities. Yet, the full extent of its geographic distribution within tropical Africa remains to be determined. This is only the second known established introduction of a non-African hoverfly species in the Afrotropics. Interestingly, the larvae of the species have been reported as predators of Aphididae and Delphacidae but we found them to be pollenivorous, which is a rare feeding mode within the subfamily Syrphinae. Moreover, it is the only known Syrphinae species of which the larvae feed on pollen from two plant species from different families (Cyperaceae and Orobranchaceae). This example illustrates how DNA barcoding may allow a fast and accurate identification of introduced species.

Com o objetivo de caracterizar a fauna local de insetos foram obtidas amostras semanais, de setembro/1999 a agosto/2000, utilizando-se armadilhas Malaise instaladas na borda da floresta e no seu interior. Uma análise temporal foi realizada com as espécies de Syrphidae coletadas há, aproximadamente, dezessete anos no mesmo local, dentro da floresta. A abundância e a riqueza de espécies também foram avaliadas. Tanto a riqueza quanto a abundância foram maiores na borda da floresta. Comparando-se os dados atuais com aqueles obtidos em 1986/1987, observa-se um decréscimo na abundância e também na riqueza de espécies de Syrphidae. A espécie mais abundante na borda foi Allograpta neotropica Curran, 1936 e no interior (1999/2000), Ocyptamus sativus (Curran, 1941). Os espécimens de Toxomerus Macquart, 1855 foram os mais abundantes na armadilha localizada na borda da floresta e os de Ocyptamus Macquart, 1834 no interior. Noventa e cinco espécies foram identificadas em 22 gêneros. Ocyptamus foi o gênero com maior riqueza de espécies (23). Na seqüência estão Copestylum Macquart, 1846 (15), Toxomerus (15) e Microdon Meigen, 1803 (10). Sete espécies foram comuns aos três levantamentos: Allograpta neotropica; Copestylum selectum (Curran, 1939); Leucopodella gracilis (Williston, 1891); Mixogaster polistes Hull, 1954; Ocyptamus funebris Macquart, 1834; Toxomerus procrastinatus Metz, 2001 e Toxomerus tibicen (Wiedemann, 1830). Três novas espécies de Microdon, uma de Toxomerus, uma de Aristosyrphus Curran, 1941 e uma de Myolepta Newman, 1838 foram identificadas. To characterize the local insect fauna, samples were obtained weekly from September/1999 to August/2000 through Malaise traps installed at the edge and inside the forest. A temporal analysis of Syrphidae species collected approximately 17 years ago at the same local, inside the forest, was made. Also, the abundance and species richness between the areas were analyzed. The syrphids were more abundant at the edge of the forest than in the interior, and the number of species as well. Comparing the current data with the data obtained in 1986/1987, a decrease in the local abundance and species richness was registered. The most abundant species at the edge was Allograpta neotropica Curran, 1936, and inside the forest (1999/2000) was Ocyptamus sativus (Curran, 1941). The specimens of Toxomerus Macquart, 1855 were the most abundant in the trap located at the forest edge, and those of Ocyptamus Macquart, 1834 in the forest interior. Ninety-five species were identified in 22 genera. Ocyptamus was the genus with the highest species richness (23). In the sequence were Copestylum Macquart, 1846 (15), Toxomerus (15) and Microdon Meigen, 1803 (10). Seven species were common among the three samples: Allograpta neotropica, Copestylum selectum (Curran, 1939); Leucopodella gracilis (Williston, 1891); Mixogaster polistes Hull, 1954; Ocyptamus funebris Macquart, 1834; Toxomerus procrastinatus Metz, 2001 and Toxomerus tibicen (Wiedemann, 1830). Three new species of Microdon, one of Toxomerus, one of Aristosyrphus Curran, 1941, and one of Myolepta Newman, 1838 were identified.

Although a predator's mass should influence the suitability of its prey, this subject has received little direct attention. We studied the capture and processing of an abundant syrphid fly Toxomerus marginatus (c. 4 mg) by 0.6- to 40-mg juvenile crab spiders Misumena vatia (Thomisidae) to determine how profitability, relative profitability (profitability/predator mass), overall gain in mass, and relative gain in mass differed with predator mass, and whether foraging changed concurrently. In multi-prey experiments, the smallest successful spiders (0.6-3.0 mg) extracted less mass from flies, and did so more slowly, than large spiders. This gain was proportionately similar to that of 10- to 40-mg spiders with access to many Toxomerus. However, many small spiders failed to capture flies. When we gave spiders only a single Toxomerus, the smallest ones again extracted mass more slowly than the large ones and increased in mass less than the large ones, but increased in mass proportionately more than large ones. Relative gain in mass from a single prey decreased with increasing spider mass. Spiders larger than 10 mg all extracted similar amounts of mass from a single Toxomerus at similar rates, but varied in time spent between captures. Thus, Toxomerus changes with spider mass from a large, hard-to-capture bonanza to a small, easy-to-capture item of low per capita value. However, Toxomerus is common enough that large spiders can capture it en masse, thereby compensating for its decline in per capita value.

Interactions among bumblebees (Bombus terricola and B. vagans Smith) and small syrphid flies (Melanostoma mellinum L. and Toxomerus marginatus (Say)) were studied on pasture rose (Rosa carolina L.). Dominance interactions took the form: bumblebees > Melanostoma > Tox- omerus. In the absence of bumblebees, Melanostoma foraged 4 1% longer, but the bees only reduced Toxomerus' foraging about 4%. The difference in bumblebee impact on the two syrphids resulted from Toxomerus rapidly returning after visits by bumblebees, while Melanostoma did not. Toxomerus used flowers most frequently when Melanostoma were not in them. Bumblebee foraging patterns appeared unaffected by either syrphid fly. Melanostoma may have a considerably greater impact than bumblebees on Toxomerus; a 14% reduction in foraging by Toxomerus was recorded in one test. This was because Melanostoma occupied flowers for several minutes at a time, while bumblebee visits lasted only several seconds. By affecting Melanostoma's activity, bumblebees inadvertently favored Toxomerus, because the latter returned quickly to flowers after bee visits; Melanostoma did not.

In the preparation of a synopsis of the North American genera of Syrphidæ, I have found several new species that could not be placed in any of our known genera. A careful study of the figures and descriptions of exotic forms has not thrown much light upon them, and I am therefore constrained to regard them as new.With the genera included in the present paper, and resuscitating Macquart's Toxomerus, the number now recorded from North America will reach sixty, all but five or six of which are in the writer's collection. Of these, but nine or ten have not yet been found east of the Central Plains, and the following, only, that are not now known west of that region, viz., Triglyphus, Senogaster, Pyrophaena, Doros, Ocyptamus, Rhingia, Brachyalpus, Somula, Temnostoma, Merapioidus, Pterallastis, Teuchocnemis and Lepidomyia, leaving nearly forty genera that occur entirely across the continent; indeed a large proportion of the species are identical from the Atlantic and Pacific regions.

Microtheca spp. (Coleoptera: Chrysomelidae) are insect pests primarily related to Brassicaceae crops. In the State of Rio Grande do Sul (RS), southern Brazil, they are found on forage turnip, Raphanus sativus L. var. oleiferus Metzg., which is commonly grown during fall/winter seasons. This work reports the predation of Microtheca spp. larvae by Toxomerus duplicatus Wiedemann, 1830 (Diptera: Syrphidae) larvae, on forage turnip crop, in Santa Maria, RS. This register provides new information about Microtheca spp. natural enemies in Brazil, which might be a new option for integrate pest management of these species.