Catching dragonflies in traps (Anisoptera)

Yellow and white plastic bowls of 18 cm diameter, filled with water containing ethyl glycol plus a detergent, attracted 171 immature adults 101 <5, 70 $ of Aeshna cyanea and of 6 Sympetrum spp. in a pine plantation in Poznan, Poland, during a 14 days warm spell (late Sept.-early Oct.). Yellow traps were 1.8 times more effective than white ones. Dragonflies were trapped when attacking Diptera or Hymenoptera alighting on the water surface. Only mature odonate individuals were able to escape and avoid drawning. It is suggested that trapping could be adopted as a supplementary technique in assessing the anisopteran fauna in areas with low vegetation.