A comparative study was conducted to test the efficiency of Centers for Disease Control and Prevention (CDC) light traps baited with either dry ice or carbon dioxide (CO₂) produced from one of three different sources in collecting mosquitoes (Diptera: Culicidae) in Thailand. Treatments consisted of dry ice pellets, CO₂ gas produced from one of three prototype CO₂ generator systems (TDA, CUBE, Moustiq-Air Med-e-Cell - MEC), and a CDC light trap without a CO₂ source. The best performing prototype from Thailand was then tested in collecting sand flies (Diptera: Psychodidae: Phlebotominae) in Greece. A total of 12,798 mosquitoes and 8,329 sand flies were sampled during the experimentation. The most prevalent mosquito species collected in Thailand were: Culex vishnui Theobald > Anopheles minimus Theobald > Culex tritaeniorhynchus Giles > Anopheles sawadwongporni Rattanarithikul & Green. By far the most prevalent sand fly species collected in Thessaloniki was Phlebotomus perfiliewi Parrot followed by Phlebotomus tobbiAdler andTheodor and Phlebotomus simici Nitzulescu. In general, theTDA treatment was the only treatment with no significant difference from the dry ice-treatment in mean trap catches. Although dry ice-baited traps caught higher numbers of mosquitoes and sand flies than the TDA-baited traps, there was no difference in the number of species collected. Results indicate that the traps baited with theTDA CO₂ generator were as attractive as traps supplied with dry ice and, therefore, the TDA CO₂ generator is a suitable alternative to dry ice as a source of carbon dioxide for use with adult mosquito and sand fly traps.