A field experiment was conducted to estimate the survival of Culex tritaeniorhynchus Giles adults before 1st blood feeding under conditions with or without predators in a rice field in central Japan. Adults were counted for 5 d after emerging in cages (2 by 2 and 1.5 m high), which were placed in rice fields during the midseason drying period. Only 10% of the adults survived until day 4 after emergence when exposed to predation, whereas > 60% of the adults survived until day 4 without predation. Lycosidae, hunting spiders, may be an effective predator of Cx. tritaeniorhynchus adults.