Bionomics of the rice leaf miner, Hydrellia griseola (Fallen), in California (Diptera: Ephydridae)

The insect now known as the rice leaf miner, Hydrellia griseola, was widely distributed in California before rice was commercially grown. This leaf miner is highly prolific in late winter and early spring, when it mines grasses associated with varied aquatic habitats. This species productivity is retarded in the spring by the natural enemies of the miner, and by the physical forces which dry up the temporary aquatic areas. The procedures normal to rice growing in April and May tend to stop the natural decline of the leaf miner population by creating new situations which lead to a buildup of this pest. However, natural control of the miner is again brought about by the onset of high temperatures during May and June. Sometimes the high temperatures normally expected at this time may be late, and the rice grower must use chemical control to protect his crop from this opportunistic pest. The investigations described in this report deal with the habits, breeding, and adaptations of the insect, particularly in the Sacramento Valley.