1900 Walter Reed, a United States Army major, was appointed president of a board "to study infectious diseases in Cuba paying particular attention to yellow fever." He concurred with Carlos Finlay in identifying mosquitoes as the agent. Ignacio Bolívar y Urrutia publishes Catálogo sinóptico de los ortópteros de la fauna ibérica. Kálmán Kertész, Mario Bezzi, Paul Stein (entomologist) and Theodor Becker published the first part of a Palaearctic Catalogue of Diptera Katalog der Paläarktischen dipteren in Budapest. 1901 William Francis de Vismes Kane A catalogue of the Lepidoptera of Ireland-the third (and first comprehensive) catalogue of the Irish macrolepidoptera. Augustus Daniel Imms General textbook of Entomology published. 10th revised edition (1977) still one of the most widely used of all insect texts. Thomas Hunt Morgan is the first to conduct genetic research with the fruit fly Drosophila melanogaster. In the Fly Room at Columbia University.

1902 Ronald Ross gained Nobel Prize for Medicine for his discovery that malaria is carried by mosquitoes. The awarding committee made special mention of the work of Giovanni Battista Grassi on the life history of the Plasmodium parasite. Charles W. Woodworth A List of the Insects of California published. Philogene Auguste Galilee Wytsman started Genera Insectorum, a multi-authored series that consisted of 219 issues, the last occurring in 1970. Otto SchmiedeknechtOpuscula Ichneumonologica. Blankenburg. William Morton Wheeler appointed curator of invertebrate zoology in the American Museum of Natural History, New York August Arthur Petry publishes Ueber die deutschen an Artemisia lebenden Arten der Gattung Bucculatrix Z. nebst Beschreibung einer neuen Art in Deutsche entomologische Zeitschrift Iris Peter Esben-Petersen publishes Bidrag til en Fortegnelse over Arktisk Norges Neuropterfauna Last sighting of Rocky Mountain locust Initiation of Hopkins Notes and Records System at the USDA

1905 Adolfo Lutz Beitraege zur Kenntniss der brasilianischen Tabaniden. Rev. Soc. Sci. São Paulo 1: 19–32, published Raphaël Blanchard Les moustiques. Histoire naturelle et médicale Paris, F.R. de Rudeval, published. Gabriel Höfner Die Schmetterlinge Kärntens (1905-1915)

1906 Adalbert Seitz, Gross-Schmetterlinge der Erde commenced. This vast work on Lepidoptera was published in German, English and French. It contained colour plates of all important species.

1907 William Lundbeck Diptera Danica. Genera and species of flies Hitherto found in Denmark commenced. Hamilton Herbert Druce On Neotropical Lycaenidae, with Descriptions of New Species. Proceedings of the Zoological Society of London. Henry Christopher McCook Nature's Craftsmen: Popular Studies of Ants and Other Insects. Lajos Abafi Magyarország lepkéi (butterflies of Hungary) 1907

1908 Edmund Reitter Fauna Germanica - Die Käfer des Deutschen Reiches commenced. This five volume masterwork remains in use today, almost 100 years from its inception. Leonello Picco Contributo allo studio della fauna entomologica Italiano. Elenco sistematico degli Emitteri finora raccolti nella Provincia di Roma. Arnold Spuler and Ernst Hofmann Die Schmetterlinge Europas (The Lepidoptera of Europe) was for decades a standard in the study of lepidoptera.

1909 George Henry Verrall Stratiomyidae and succeeding families of the Diptera Brachycera of Great Britain - British flies published. Carlos Chagas observed the peculiar infestation of rural houses in Brazil with Triatoma, a "kissing" bug, later demonstrating that it was the vector of Trypanosoma cruzi, and he was able to prove experimentally that it could be transmitted to marmoset monkeys that were bitten by the infected bug. His description of the new disease was to become a classic in medicine and brought him domestic and international distinction. Charles Nicolle reasoned that it was most likely lice that were the vector for epidemic typhus. He tested his theory by infecting a chimpanzee with typhus, retrieving the lice from it, and placing it on a healthy chimpanzee. Within 10 days the second chimpanzee had typhus as well. Antonio Berlese Volume I of Gli insetti loro organizzazione, sviluppo, abitudini e rapporti con l'uomo (Volume 2 1925). Arnold Pagenstecher Die geographische Verbreitung der Schmetterlinge published in Jena. Foundation of Journal of Entomology by Charles Fuller Baker, one of the first revues of economic entomology. Murinus Cornelius Piepers, Pieter Cornelius Tobias Snellen and Hans Fruhstorfer. The Rhopalocera of Java commenced. Completed 1918.

1910 Gilbert John Arrow published the first volume of The Fauna of British India, Including Ceylon and Burma. Lamellicornia 1. Cetoniinae and Dynastinae. Arrow wrote five volumes of this classic work. Hans Ferdinand Emil Julius Stichel Lepidoptera Rhopalocera. Fam. Riodinidae. published in J. Wytsman Genera Insectorum 112A completed 1911). Hans Fruhstorfer published Family Pieridae in Adalbert Seitz's Macrolepidoptera of the World Thomas Hunt Morgan begins using Drosophila melanogaster as a model organism for genetics studies

1912 Per Olof Christopher Aurivillius wrote Part 39 of Catalogus Coleopterorum Cerambycidae: Cerambycinae (1912). Aurivillius worked on world insects.

1913

Charles Paul Alexander A synopsis of part of the Neotropical Crane-flies of the subfamily Limnobinae (Tipulidae). Erwin Lindner joined the State Museum of Natural History Stuttgart. Otto Kröber Therevidae.Genera.Ins published. Karl Eckstein Die Schmetterlinge Deutschlands mit besonderer Berücksichtigung der Biologie commenced (finished 1933). G.D. Hale Carpenter joined the London School of Hygiene and Tropical Medicine, and took the Doctor of Medicine examination in 1913 with a dissertation on the tsetse fly (Glossina palpalis) and sleeping sickness.

1914 Friedrich Georg Hendel Die Arten der Platystominen. Abh. Zool.-Bot. Ges. Wien 8 (1): 1–409, 4 pls. published Filippo Silvestri Contribuzione alla conoscenza dei Termitidi e Termitofili dell'Africa occidentale. Bollettino del Laboratorio di Zoologia General e Agraria, Portici.

1915 Nathan Banks A Treatise on the Acarina, Or Mites the first comprehensive English handbook on mites. Reginald Punnett publishes Mimicry in Butterflies. Ottoman Syria locust plague in the Levant.

1916 The Japanese beetle, Popillia japonica, was first discovered in the United States in Riverton, New Jersey during mid-August 1916. 1919

Boll Weevil Monument erected in Enterprise, Alabama 1920 Alfred Kinsey became Professor of Entomology at Indiana University Bloomington. Ernst Jünger publishes In Stahlgewittern, The Storm of Steel. Enrico Adelelmo Brunetti The Fauna of British India, Including Ceylon and Burma. Diptera 1. Brachycera published. Charles Thomas Brues Insects and Human Welfare published. G.D. Hale Carpenter published: A Naturalist on Lake Victoria, with an Account of Sleeping Sickness and the Tse-tse Fly; 1920. T.F. Unwin Ltd, London; Biodiversity Archive

1921 Günther Enderlein Über die phyletisch älteren Stratiomyiidensubfamilien (Xylophaginae, Chiromyzinae, Solvinae, Beridinae und Coenomyiinae). Mitt. Zool. Mus. Berl. 10: 150-214 published.

1923 Auguste-Henri Forel publishes a myrmecological 5-volume magnum opus, Le Monde Social des Forimis

1924

Frederick William Frohawk's Natural History of British Butterflies published.

1925 Frank M. Carpenter begins work on the Elmo Permian fossil fauna. Josef Fahringer Opuscula braconolocica (4 parts, finished 1937) begun.

1927 Ronald A. Senior-White and Robert Knowles (entomologist) Malaria: Its Investigation and Control, with Special Reference to Indian Conditions. Calcutta: Thacker, Spink and Co published. José María Hugo de la Fuente Morales Tablas analíticas para la clasificación de los coleópteros de la Península Ibérica. Barcelona Imprenta Altés, published. Zeno Payne Metcalf commenced (as overall editor and author of the Homoptera sections) General Catalogue of the Hemiptera. Completed 1971.

1928 Jan Noskiewicz with G. Poluszynski Embryologische Untersuchungen an Strepsipteren. I. Teil: Embryogenesis der Gattung Stylops Kirby. Akad. Umiejetnosci.. Leopold III of Belgium a keen amateur entomologist collects in the Dutch East Indies(1929-1929) Guido Grandi founded the Institute of Entomology at the University of Bologna (l'Istituto di Entomologia dell'Università di Bologna). Fossil that is sometimes considered as oldest known insect, Rhyniognatha hirsti named by Robert John Tillyard. Alexander Kirilow Drenowski The Lepidoptera fauna on the high mountains of Bulgaria Sbornik bulg. Akad. Nauk. 23: 1–120, 1 map, published.

1930 Camillo Acqua Il bombice del Gelso:Nello stato normale e patologico nella tecnica dell'allevamento e della riproduzione. (Industria della preparazione del seme Bachi)-Enc. tela. Casa Ed. di Giuseppe Cesari, published. This was an important contribution to the literature on sericulture.

1931 Georg Hermann Alexander Ochs publishes Über die Gyriniden-Ausbeute der Deutschen Limnologischen Sunda-Expedition mit einer Übersicht über die Gyriniden-Fauna Javas und Larvenbeschreibungen. Shonen Matsumura 6,000 illustrated Insects of Japan-Empire.

1932

A Practical Handbook of British Beetles by Norman H. Joy published by Witherby. Alfred Balachowsky Étude biologique des coccides du bassin occidental de la Méditerranée published in Paris by Lechevalier and Fils.

1934 René Malaise invents the Malaise trap. Vincent Brian Wigglesworth, the "Father" of Insect Physiology, writes the first book on insect physiology, The Principles of Insect Physiology. Antoni Władysław Jakubski Czerwiec polski "Polish cochineal". Monograph on the Polish cochineal.

1935 Gerhard Schrader discovers the powerful insecticides called organophosphates Walter Rothschild gives his insect collection, one of the world's largest collections of Lepidoptera, to the Natural History Museum.

1936 The Natural History Museum, London acquires the James John Joicey collection of Lepidoptera.

1938 Lucien Chopard La biologie des orthoptères (Paul Lechevalier, Paris). Ângelo Moreira da Costa Lima commenced Insetos do Brasil, v. 1-11. Completed 1960.

1940 Vladimir Nabokov begins organizing the butterfly collection of the Museum of Comparative Zoology at Harvard University. Ruggero Verity commenced Farfalle, in English Butterflies, of Italia (five volumes, 1940–1953). René Jeannel Faune cavernicole de la France, in English The Fauna of the Caves of France, published. Japanese army drops plague-infested flea bombs in Zhejiang, China

1941 Zoltán Szilády A magyar birodalom legyeinek szinopszisa. VI. Talpaslegyek, Clythidae (Platypezidae); VIII. Lauxaniidae [Synopsis of the flies of the Hungarian empire]. Adolf Horion Faunistik der Mitteleuropäischen Käfer commenced. Completed 1974.

1942 Woodhouse, L. G. O. & George Morrison Reid Henry. The Butterfly Fauna of Ceylon. Government Record Office, Colombo Ernest Gibbins killed in Uganda by tribesmen.

1943 André Badonnel Faune de France. Psocoptères. Paris. Paul Lechevalier 1943. Leopold Fulmek Wirtsindex der Aleyrodiden- und Cocciden- Parasiten Entomologische Beihefte 10: 1–100.

1944 Enrica Calabresi commits suicide in Florence. Vladimir Nabokov describes the Karner blue.

1945 Edmund Brisco Ford Butterflies published, seminal introduction to the study of butterflies and their genetics. Cynthia Longfield The Odonata of South Angola. Arquivos do Museu Bocage, 16, Lisboa.

1946 Institut National de la Recherche Agronomique founded.

1947 Carlo Alonza became director of the Muséum de Gênes. Launch of National Malaria Eradication Program in the U.S.

1949 Pierre-Paul Grassé ed. Traité de Zoologie Tome IX. Insectes. Paris, 1949. 1118 p. 1950 Maynard Jack Ramsay becomes Port Entomologist on Staten Island. Mahadeva Subramania Mani founded the School of Entomology at Agra, India.

1951