STUDIES ON THE FAUNA OF CURAÇAO AND OTHER CARIBBEAN ISLANDS: No. 50. The Heteroptera of the Netherlands Antilles - I Foreword Gerridae, Veliidae,Mesoveliidae (Water Striders) by R.H. Cobben (Laboratoriumvoor Entomologie, Landbouwhogeschool, Wageningen) The data concerning the heteropterous fauna of the Netherlands Antilles from which the following series of contributions has been compiled are chiefly the result of an entomological study trip lasting from September 1956 until July 1957. The investigations were carried out under the auspices of, and sponsored by, the Suriname Natuurwetenschappelijke Studiekring voor en de Neder- landse Antillen (Foundation for Scientific Research in Surinam and the Netherlands Antilles), with financial assistance fromthe Govern- ment of the Netherlands Antilles. I wish the Foundation for to express my appreciation to making it for undertake this possible me to mission. The periods of residence on the islands concernedwere as follows: Curagao 7th October - 20th November 1956; 12th January - 1st April 1957; 5th June - 7th July 1957. Bonaire 3rd May - 5th June 1957. Aruba 1st April - 3rd May 1957. - St. Martin 20th November - 9th December 1956; 9th 12th January 1957. Saba 9th - 27th December 1956. St. Eustatius 27th December 1956 - 9th January 1957. 3 As be from the field carried in can seen above, surveys were out Curasao, the largest island of the Netherlands Antilles (425 sq. km), during three different periods, viz., in the wet season, the tran- and the The work of sitional season, dry season. collecting went on in all the various the last so intensively, habitats, up to very day, that in the finalweeks of our stay in Curasao no specimens whatever were caught which did not belong to species we had already en- countered. As a result of this we feel that our Curagao collections the fauna are fairly complete and, as regards hemipterous proper, more representative than the collections made from the other islands. The sampling on the latter can only claim to be reasonably when considered of the situation complete as pictures at a certain time. Since, however, on each of the islands it is possible to findnatural or artificial localities where the influence of the dry season on flora and fauna becomes considerably reduced, the data collected will nevertheless enable a comparison to be made betweenthe hemipter- ous fauna of Curagao on the one hand and that of the remaining, the other. smaller islands on the fauna and In our investigations emphasis was placed on ecology of the Heteroptera or true bugs, to which the present series relates, and the Homoptera Auchenorrhyncha or leaf hoppers s.l., form of another of which are to the subject series publications. insects of other orders also and However, many were collected, special attention was paid to insect pests. 1957 onwards I in the work From 15th January was assisted by whose was the above-mentioned my wife, passage arranged by Foundation, with financial help from the Stichting Wetenschappelijk Onderzoek Suriname- Nederlandsle Antillen WOSUNA (Netherlands Foundation for the Advancement of Research in Surinam and the Netherlands Antilles). Mrs. COBBEN (formerly Miss L. MEIER), herself a graduate of Wageningen, took care of the experiments carried out with 35 species of Hemiptera, and made numerous Faure preparations of the larval stages collected during our surveys. A short historical of the research the Netherlands summary entomological on of 1950 been & WAGE- Antilles carried out up to the end has compiled by GEIJSKES NAAR HUMMELINCK (1951), IXth Intern. Congr. Entom. Amsterdam, 4 pp.). Since 5 then, further papers of a pure entomological nature concerning these islands have appeared in the present Series, viz., in Volume IV (JONGE POERINK, Cicindela; VAN DER KUYP, Culicinae; BURGERS, Anastrepha); Volume V (MARCUZZI, Tenebrionidae; VI VAN DER KUYP, Culicinae) ; Volume (WAGENAAR HUMMELINCK,. Megacephala); Volume IX (WYGODZINSKY, Thysanura and Machilida; MARCUZZI, Tenebrionidae), and VolumeX (BUCK, Anthicidae). in different Attention is drawn to the following terms, which are often used meanings but which here cover the areas as stated: West Indies Antilles, Bahamas, Florida Keys, Bermuda, Cayman Islands, Swan Island, Old Providence, San Andres Antilles from Cuba to Trinidad and Aruba Greater Antilles from Cuba to Puerto Rico .... Lesser Antilles from Virgin Islands to Trinidad and Aruba Windward Group . from Virgin Islands to Grenada (Bovenwindse Eilanden, Islas de Barlovento, lies sur le Vent, Inseln iiber dem Winde) Leeward Islands . (British usage) from Virgin Islands to Dominica Windward Islands . (British usage) from Martinique to Grenada Los to Leeward Group .... from Testigos Aruba (Benedenwindse Islas de Eilanden, Sotavento, lies sous le Vent, Inseln unter dem Winde) The islands of the Leeward Group (Aruba, Curasao, Bonaire) lie of low the north within an area rainfall which extends along of South America. Rain is in as well coast very irregular quantity as in distribution; it falls chiefly in heavy, short-lived showers, it is which are often only of local importance. Generally speaking, scanty from February to September. The total amount of precipi- tation during these months is about200 mm in Curasao and Bonaire, and less than 150 mm in Aruba. In the 'rainy season', from October the 300-350 to January, average precipitation amounts to mm. The islands of the Windward Group (St. Martin, Saba, St. Eusta- receive abouttwice much rain those of the Leeward tius) may as as about 1100 But there Group, viz., mm per year. too, precipitation is erratic from to and month to and very year year month, long droughts may occur. 7 The average annual temperature in Aruba, Curasao and Bonaire is 27.5°C. September is considered to be the hottest month (average monthly maximum 32°C, minimum 26°C), January and February the coolest months (average monthly maximum 28.7°C, minimum 23°C). On St. Martin, Saba and St. Eustatius - situated about 900 km farther northeast - the months of July, August and September are the hottest (average maximum 30.5°C, minimum 26°C), January and February the coolest (average maximum 27.5°C, minimum 22.5°C). The prevailing trade winds are easterly. These sea winds blow with diminished force the very steadily, only slightly even during night, at a mean velocity of about 5-7 m/sec. in the LeewardGroup, 3.5-5 in the Windward Group. The first lie just south of the most hurricane the second hurricane southerly track, while can expect a period which usually lasts from July until September. About one third of the Leeward Group area consists of limestone rock. The non-calcareous soil consists of igneous and sedimentary rock of varying composition. In the Windward Group limestones are common on St. Martin, while absent and form they are on Saba, only a peculiar, steeply dipping wall on the south coast of St. Eustatius. Owing to the unfavourablerainfall conditions the vegetation has a pronounced xerophytic character. On the islands of the in Leeward Group, desert-like conditions even prevail some spots, and luxuriant be few a more vegetation is only to found on a sheltered or irrigated places. In the Windward Group, on the other hand, a luxuriant vege- tation the of about 850 occurs on higher parts Saba (up to m) and St. Eustatius (up to 600 m). This is caused by the much higher rainfall, whose values have been recorded in the lowlands, and the clouds which often are surrounding the mountain tops. Further data environmental factors Antilles be found on in the Netherlands may the Fauna II IV in Studies on of Curasao, etc., Vols. I (1940, No. 1), (No. 4), (1953, No. 17), and V (1954, No. 23), VI (1955, No. 25), and VII (1957, No. 29); VEENEN- 8 BOS' A Soil and Land Capability Survey of St. Maarten, St. Eustatius, and Saba and the Netherlands Antilles — (1955) ; STOFFERS' The Vegetation of published by the Foundation for Scientific Research in Surinam and the Netherlands Antilles. Looking back on an unforgettable sojourn in the West Indies, we would like here to express our thanks to all who helped to make the expedition such a success, and in particular to: Dr. P. WAGE- NAAR HUMMELINCK, promotor of the trip, for his assistance, which was excellent in all respects; Professor J. DE WILDE, Directorof the Laboratoriumvoor Entomologie, Wageningen, for the ample facili- ties he Mr. E. gave us; J. HEESTERMAN, who smoothed my path the of in the fabulous of at outset my venture, island Trinidad; Dr. G. A. C. HERKLOTS and Mr. J. WOOLLCOMBE, who arranged comfortable quarters for me in the Imperial College for Tropical Agriculture at St. Augustine, Trinidad, and Professor T. W. KIRK- in PATRICK, who made available to me working accomodation his laboratory, where I was able to prepare for the projected surveys by consulting collections and the library; the GOVERNMENT of the Netherlands Antilles for help in the matters of transport and housing; Dr. J. S. ZANEVELD, at that timeDirector of the Caribbean Marine Biological Institute (Carmabi), Curasao, who provided us with a large workroom for experimental work, and who, together with his alert of the staff, was always to opportunities helping us; Managing Director of what was then the PETROLEUM INDUSTRIE MAATSCHAPPIJ (C.P.I.M.; now: Shell Curasao) and the GeneralManager of the AREND PETROLEUM MAATSCHAPPIJ ('Eagle'), Aruba, for the provision of accommodation; Mr. B. J. DE JONG, graduate biologist, for valuable information concerning Curasao insects and for his help in identifying plants; and Frater M. ARNOL- who made with the local flora. We also DO, also us acquainted are very grateful to Messrs. E. VAN DER KUIP (Aruba), E. PIETERS KWIERS (Bonaire), M. MELTSER (St. Martin), J.FERWERDA (Saba) and P. A. VAN DEN HEUVEL (St. Eustatius) for their greatly valued help in researches the and the members our on respective islands, also to of the NATUURWETENSCHAPPELIJKE WERKGROEP NEDERLANDSE ANTILLEN (Natural Science Study Group for the Netherlands An- tilles), for their assistance and interest, which made our task easier.