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In deze publikatie worden de resultaten vermeld van een onderzoek naar de galmugfauna van rode en witte klaver in Nederland. Laboratoriumproeven en veldwaarnemingen hebben uitgewezen, datDasyneura gentneri Pritchard,D. leguminicola (Lintner) enTricholaba trifolii Rubs. zich voeden ten koste van het zich ontwikkelende klaverzaad. Hun optreden is echter niet van economische betekenis voor de teelt van klaverzaad in Nederland. Dasyneura trifolii (F. Loew) verwekt bladgallen op witte klaver, maar door deze aantasting worden de planten niet in hun normale groei belemmerd. De larven vanLestodiplosis pallidicornis Kieffer en vanPhaenobremia aphidivora (Rubs.) zijn roofvijanden; zij voeden zich respectivevelijk met larven van allerlei andere galmugsoorten en met bladluizen, die op rode en witte klaver leven. De soortenAmetrodiplosis sp.,Clinodiplosis sp. enIsodiplosis deutera Milne f.n.sp. leven in de bloemhoofdjes van rode klaver, maar hun juiste levenswijze is nog niet bekend.Milne (1960) enBarnes (1946) vermelden van witte en rode klaver in Engeland nog de soortenBrachyneura squamigera (Winnertz),Campylomyza ormerodi (Kieffer),Clinodiplosis leguminicola Milne enGiardomyia britannica Milne. Deze soorten werden door ons in Nederland tijdens het onderzoek niet gevonden. Deze publikatie vermeldt verder bijzonderheden inzake de levenswijze, de morfologie en de ontwikkelingscyclus van de behandelde galmugsoorten, terwijl ook aandacht is besteed aan hun economische betekenis voor de teelt van witte en rode klaver in Nederland.

This part of the survey of economic important gall midges in the Netherlands deals with the species injurious to vegetable crops.

This paper deals with some experiences gained with the use of all metal conical traps in the study of some gall midge flight periods. These conical traps have been described in detail byvan Dinther (1953). The present writer constructed a modification which proved to be very useful for phenological observations on the raspberry cane midge (Thomasiniana theobaldi Barnes), the button top midge of basket willows (Rhabdophaga heterobia H. Lw.) and aClinodiplosis species on poppy. The new type consists of a frame made of zinc, which is built up by two hoops (fig. 1) with diameters 2.5 and 11 inches. The upper hoop is 1 inch, the lower hoop 4 inches wide. The height of the frame is 14 inches. The hoops are connected by two strips of zinc (3) alternating with two strips of metal gauze (4). At the lower hoop four zinc legs are attached to press the trap firmly into the soil. A bottomless jampot (5) is placed over the upper hoop. In this pot a small plastic cone (6) is fixed with Bostik adhesive no. 1775. Small holes at the lower sides enable a good drainage in case of a heavy shower. The gall midges are positively phototropic and move up the cone into the pot. The plastic cone prevents the midges from finding their way out and they can easily be collected by means of an exhauster. The lid of the pot consists of muslin to avoid condensation of water as much as possible. If the midges cannot be collected daily, they may be kept in good condition for taxonomic studies by filling the pot partially with a mixture of glycerin and water. In this case the drainage holes in the plastic cones must be omitted. The dates of emergence in these traps agreed very well with the normal field observations and this will lead to using this new type at the Institute for Phytopathological Research for future phenological observations on gall midges.