Evolution of Dispersal Traits of Adult Stream Insects

Elaine Langone Center, Terrace Room

Mating and dispersal occur during a stream insect’s adult life stage. An insect can disperse from one stream to another by flying along the stream or through the terrestrial habitat between streams. Insects can also fly at different heights. Most insects stay slightly above the surface of the water, but few studies have examined flight through the forest canopy. Stream insects may have evolved different body morphologies and behaviors to better help them disperse through or above the forest. We tested if the abundance of adult caddis flies, stone flies, and mayflies differed between the tree canopy and above the surface of the stream. We collected larval and adult invertebrate samples from five different sites among Mosquito Creek and Remmington Run in South Williamsport, PA. Adults were collected over a period of fourteen days using canopy and malaise traps in the summer of 2017. We found a lower number of adult insects in the canopy than directly above the surface of the stream, but insects were always present in the canopy. Our results suggest that adult stream insects do disperse in tree canopies. Future work will further examine assemblage composition and species specific wing morphologies.