The Growth of Coenis horaria (L.), Leptophlebia vespertina (L.), and L. marginata (L.) (Ephemeroptera)

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SUMMARY.

  • 1 The results obtained from the measurements of the growth in length of three Ephemeropteran nymphs are described. The nymphs were Coenis horaria (L.), Leptophlebia vespertina (L.), and L. marginata (L.).
  • 2 The measurements were made with a projection apparatus.
  • 3 The growth curves show that in winter Coenis does not grow, while in Leptophlebia growth continues.
  • 4 The factors responsible for this difference in growth appear to be food and temperature. Both Leptophlebia and Coenis are detritus feeders, but Coenis evidently requires a detritus enriched by the fragments of filamentous littoral algae.
  • 5 The renewal of growth in Coenis coincides with the increased growth of littoral algae and rise of temperature in spring. At this time the gut contents of Coenis contains large quantities of filamentous algae.

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