LIFE-HISTORY PATTERNS OF ONYCHOGOMPHUS-UNCATUS (CHARPENTIER) (ANISOPTERA, GOMPHIDAE)

The results of a 4-yr study are reported. Data from Surber-samples of 3 running waters in southern France were compared with results from fi eld enclosure experiments. Egg development lasted about one month unde r field conditions and two weeks at 25 degrees C in the laboratory. O. uncartus has usually but not strictly 13 larval instars and a 3-yr li fe cycle. Each year emergence started in early June. The emergence cur ve was typical of a summer sp. Several aspects of seasonal regulation are discussed. The monitoring of population structure indicated a high mortality of final instar larvae (up to 99%) during winter. This mort ality differed between the sample sites of one of-the running waters. These differences depend on prey availability and on larval density. A field enclosure experiment revealed density dependence of larval size and growth.