Abstract
Orthellia pacifica ZIMIN was tested for the effects of larval intraspecific competition. Newly hatchaed larvae were transferred to cattle dung and reared until adult emergence at thirty-one densities of between 1 to 301 larvae per 50 g of dung. A s the density increased, reduction in the size of emerged adults, increaseing mortality and shortening of the developmental period from larvae to adults were observed. These density effects, however, did not begin to occurat the same density levels. The adult size and developmental period began to decrease at the density of 21 larvae. On the other hand, increase in the mortality did not occur until the density of 121 larvae where the adult size had reached almost the lowest limit. These findings were discussed in relation to competitive advantage and larval habitat characteristics.
