An improved portable immature mosquito concentrator system was developed and evaluated under laboratory and field conditions. In laboratory tests using 2500 Culex pipiens Linnaeus immatures, 99.8% of the specimens were captured by the concentrator system. When Aedes taeniorhynchus (Wiedemann) immatures were used, 93.7% of the specimens were captured. Excluding 1st instar larvae, the system caught 99.9% of the 4000 specimens used in the combined test. During field evaluation of the system, the contents of 100 dips made in a salt marsh habitat were concentrated into 10 collection and storage vials. Of 6803 Ae. sollicitans (Walker) collected larvae, 100% of the specimens were captured by the improved immature mosquito concentrator system.
