Caddisflies (Trichoptera) of Southeast Asia are analyzed with special attention to the Sunda Islands to evaluate the zoogeographic effects of island isolation and potential influence from the neighboring continental faunas. Results of recent Trichoptera collections and synopsis of previously published data for the islands of Java, Bali, and Lombok are presented along with their zoogeographical interpretation on the islands as well as on the adjacent regions. A total of 202 Trichoptera species is known to occur on the three islands; 146 species are known in Java, 73 in Bali and 61 in Lombok. 43 species are common to Java and Bali, 27 to Java and Lombok, 30 to Bali and Lombok, 70 to Java and Sumatra. A significant decrease in species richness has been observed in comparison to the Asian mainland. The caddisfly fauna of the three islands is of Asiatic origin, no Australian influence was noted. The well-known Wallace’s line does not act as a faunistic border between Bali and Lombok for Trichoptera.