The development of large suction traps for airborne insects

Small suction traps for estimating the density of airborne insects, and its fluctuations, in relatively sheltered situations, e. g. in crops, have already been designed and used. Larger, more powerful traps have now been developed for use in more exposed situations where insect densities are very low, or where winds are relatively strong, e. g. high in the air. Because of the large sample obtained they also enable very short-term density fluctuations to be followed. The radical modifications of design and the special problems encountered in the operation of very large traps are described.