Over het gebruik van vangkegels bij het galmugonderzoek

Abstract

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.