Distribution of the larvae of blackflies (Diptera: Simuliidae) at Doi Inthanon National Park, northern Thailand.

The larvae of seventeen Simulium species consisting of thirteen known species, three unnamed species and one new species were distributed in various localities with different habitats at 400-2,460 meters above sea level in Doi Inthanon National Park, Chiang Mai Province, northern Thailand. Simulium caudisclerum, S. sp G and S. sp H were restricted to the high altitude of 2,460 m at the cool Ang Kha habitat of the summit of Doi Inthanon. On the other hand, S. nakhonense and S. rudnicki occurred only at low altitudes from 400 m-700 m. Some Simulium species such as S. fenestratum, S. asakoae, S. inthanonense and S. sp J were found in the warmer localities at 1,010 m-1,280 m altitudes. Moreover, S. feuerborni and S. rufibasis were widely distributed species at different altitudes from 700 m-2,460 m and 1,010 m-2,300 m respectively. Therefore, the distribution and abundance of Simulium species seem to correlate with altitudes as well as micro-habitat factors such as water temperature and water velocity.