The life cycle of an introduced caddisfly,Cheumatopsyche pettiti (Banks) (Trichoptera: Hydropsychidae) in Waikolu Stream,Molokai, Hawaii

Hawaiian streams contain some of the most unique species of aquaticinvertebrates known. In the 1960's a North American net spinningcaddisfly, Cheumatopsyche pettiti was inadvertentlyintroduced and is found in most perennial streams on Oahu, Maui,Molokai and Kauai. We investigated the life cycle of thistemperately evolved caddisfly in Waikolu Stream, Molokai. The lifecycle of C. pettiti was interpreted as probably multivoltinewith continuous recruitment throughout the year. At all samplingdates, instars I–V were present as well as pupae and adults.Detritus accounted for >50% of the gut contents of all larvae.Diatoms and other algae accounted for the remaining 50% of thediet. Cheumatopsyche pettiti has also apparently adapted toextremes in stream flows by building smaller capture nets andrudimentary retreats, usually on bedrock or firmly embeddedcobble.