A Floating Adhesive Trap for Neustonic Insects

Abstract

Continuous quantitative sampling of neustonic insect populations presents some difficulties. Many insects of the neuston are not attracted to light traps or are attracted only during certain types of weather. Some neustonic insects are active both day and night, but some species are either diurnal or nocturnal in their activity. In addition, the nocturnal habits of a large majority of neustonic insects are unknown. Conceivably, some of these problems could be overcome by systematic use of special floating traps. One of these employs a detergent to trap the insects. This trap, devised by Grigarick (1959), consists of a detergent solution contained in a shallow pan held within a wooden frame float. The float is anchored on the corners with dowels and can be equipped with a rain shield. Grigarick designed the device to trap adults of Hydrellia griseola (Fallen) (Diptera: Ephydridae), which alight upon and skate over the water surface. Flies attempting to settle upon the trap solution sink, probably because of the destruction of their tarsal hydrofuge oils and the decrease of the surface tension by the detergent.