A study on embryonic development and larval growth of Sympetrum danae (Sulzer) at two artificial ponds in Lower Austria (Anisoptera: Libellulidae)

Newly laid eggs were collected at Oberradlberg, Lower Austria (Sept. 5,1981),and reared under natural conditions in a garden pond. The embryonic development was completed in 217-239 days, at a mean temperature of 10,8° C. The process is briefly described. A diapause stage took place immediately prior to blastokinesis. All eggs hatched within 22 days, showing a high degree of synchronisation. — The newly hatched larvae were reared in tubes in a garden pond. Ten instars were observed. The average body lenght increment per moult was proportionately constant at 27% approx. The larval growth could be well described in terms of a power law. The mean specific growth rate, which ranged from 0.8 to 1.8% lenght increment day-1, is compared with the growth rates of other Sympetrum spp. The lifecycle of. S. danae is briefly described, and the overwintering strategies in the genus are reviewed.