. Elements of ecology. Ecology. 170 Temperature the white mayfly, Eplioron album, must be chilled to within a few de- grees of freezing for several weeks (or subjected to a few days of actual freezing) for good hatching to be assured. As a result, this insect cannot extend its range in the eastern part of the United States farther south than 40° N latitude. The eggs of the Australian grasshopper will not continue growth beyond a certain stage unless they are exposed to low temperatures within the range that will permit diapause development to proceed rapidly (5-13°C), and later, to high temper
. Elements of ecology. Ecology. 170 Temperature the white mayfly, Eplioron album, must be chilled to within a few de- grees of freezing for several weeks (or subjected to a few days of actual freezing) for good hatching to be assured. As a result, this insect cannot extend its range in the eastern part of the United States farther south than 40° N latitude. The eggs of the Australian grasshopper will not continue growth beyond a certain stage unless they are exposed to low temperatures within the range that will permit diapause development to proceed rapidly (5-13°C), and later, to high temperatures (17-35°C) which permit morphogenesis to go forward (Fig. ). This dependency. 20 Temperature, °C From Andrewaitha, 1952, copyright Cambridge Univ. Press Fig. The influence of temperature on (A) diapause development and (B) post-diapause morphogenesis in the embryo of the grasshopper, Austroicetes cruciata. Solid line: eggs from South Austraha; broken line: eggs from West Australia. on chilling is nicely attuned to the normal life cycle of this grasshop- per. Since the insect reaches the diapause stage at the beginning of winter, it is in the condition to endure best the severest cold weather of the year and also to take advantage of low temperatures for the completion of diapause development. Other species in which dia- pause occurs during later stages of the life history exhibit a different timing in their adjustments to the ecological conditions of their habi- tat. The eggs of the moth, Euproctis, hatch during July, and dia- pause does not take place until the larvae have reached the second or third instar. By the time the animals enter diapause autumn has arrived and the species overwinters in the larval stage. In New England the gypsy moth pupates in summer, and develop-. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not per
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