AERIAL DISPERSAL OF INSECTS BETWEEN AND TO ISLANDS IN THE GALAPAGOS ARCHIPELAGO, ECUADOR

Active or passive movement of insects through the air is probably thei r most common means of dispersal to oceanic islands. Use of aerial net s suspended on boats documents the presence of insects in the air betw een the islands of the Galapagos Archipelago during the 1991-1992 El N ino climatic event. At least 50 species of terrestrial arthropods in n ine orders were captured. The most abundant families were Aphididae, A leyrodidae and Psyllidae (Homoptera), Encyrtidae and Formicidae (Hymen optera), and Sciaridae and Ceratopogonidae (Diptera). The moist condit ions and winds during a strong El Nino probably create the most favora ble circumstances for aerial movement of insects between islands of th e Galapagos and for movement from the tropical American mainland to th e Archipelago.