Title: THE LIFE HISTORIES OF THREE SPECIES OF <i>LESTES</i> (ODONATA: ZYGOPTERA) IN SASKATCHEWAN
Abstract: Abstract In Saskatchewan, Lestes unguiculatus Hagen, L . disjunctus disjunctus Walk., and L . dryas Kirby overwinter as eggs in a late stage of embryonic development. The embryos enter diapause in September and, in this condition, can survive exposure to temperatures as low as −20 °C. Under field conditions adequate snow cover is necessary to prevent egg mortality due to desiccation or exposure to air temperatures lower than −20 °C. Post-diapause development can take place at 0 °C but does not occur until the eggs are wetted as the pond fills with runoff water in the spring. Hatching in L . disjunctus and L . unguiculatus is highly synchronous and occurs when the water temperature is about 10 °C. Larval development is completed in about 60 days. Emergence is highly synchronous and is virtually complete within 10 days. Sexual maturation requires 16 to 18 days. Oviposition immediately follows copulation while the pair is still in tandem. Eggs are laid only in green stems of Scirpus L., between 5 and 60 cm above the water surface. The stems selected are those either growing in small groups or bordering larger stands. The significance of the observations is discussed in terms of the species’ ability to survive the climatic extremes of central Canada.
Publication Year: 1974
Publication Date: 1974-12-01
Language: en
Type: article
Indexed In: ['crossref']
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Cited By Count: 50
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