Butterflies - Aestivation Or Summer Lethargy
( Originally Published 1917 )
In some species of butterflies there is a special adaptation to passing through the hottest part of the slimmer season in a state of lethargy which is suggestive of the torpor of the hibernating period. This phase of butterfly existence has not been extensively studied and there are indications that it exists more generally than has been commonly sup-posed. It has been noticed even in northern New England that some of the Angle-wings seek shelter and become lethargic during August. Apparently this is an adaptation to single broodedness, helping to carry the species through the year without the exhaustion incident to the continued activity of the butterfly.
In more southern regions, especially in the hot, dry climates where vegetation withers in midsummer, it is well known that some caterpillars become lethargic, remaining inactive until the fall rains start vegetation into growth. The Orange-sulphur butterfly is a good example of this.
This summer lethargy offers excellent opportunity for careful study. Any observer who finds a butterfly hidden away in summer under boards, the bark of a tree, or in a stone pile should look carefully to see what species it is and how the butterfly behaves. Such observations should be sent to the entomological journals in order that our knowledge of the subject may be increased.