File:Nature sketches in temperate America, a series of sketches and a popular account of insects, birds, and plants, treated from some aspects of their evolution and ecological relations (1911) (14568619108).jpg

Identifier: cu31924024546263 (find matches)
Title: Nature sketches in temperate America, a series of sketches and a popular account of insects, birds, and plants, treated from some aspects of their evolution and ecological relations
Year: 1911 (1910s)
Authors: Hancock, Joseph Lane
Subjects: Plant ecology Animal ecology Animal behavior Birds Insects
Publisher: Chicago, A. C. McClurg & Co.
Contributing Library: Cornell University Library
Digitizing Sponsor: MSN

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Text Appearing Before Image:
ot be said of manyinsect larvae, flies, beetles, locusts, grasshoppers, katydids,dragon-flies, and so forth, all of which are preyed upon freelyby birds. Young birds are taught to some extent by the parentswhat to eat, and as a result there has arisen a kind of specialdiet for each species of birds. From this line of reasoning it follows that a former promiscu-ous diet among birds might become restricted, and this meansthe exclusion of some distasteful butterflies. The latter mayhave been eaten in generations past, but are now immune.If birds were the selective factor in perfecting the supposedmimicry or resemblance of the Viceroy butterfly to the Monarch,the bird-eating factor must have exercised the selective influencein time past, more than at present. At least it is so deducedfrom observations. While the adult butterfly enjoys a largeshare of immunity from birds, I am not in possession of factsas to how much destruction is caused the larvae and pupae by MIMICRY, \YITH EXAMPLES 125
Text Appearing After Image:
The Jtrerot/ Caterpillar nhout ready to pupate. It has fed on t/ie Icaies of the heart-ahaped willow. Shortly after this photograph iva.t made it transformed into the pupa, as shown on the next page. 126 NATURE SKETCHES IN TEMPERATE AMERICA birds. Nor have I a knowledge of the amount of destructionoccasioned by birds to the eggs. But from actual observation Ihave seen numbers of the pupa and eggs thdt were parasitized byHymenoptera. It is in these stages that the butterflies generallysuffer the greatest amount of destruction from animal enemies. The Monarch is seem-ingly much more abundantthan its mimicker. This isone of the special condi-tions under which mimicryexists. The vital period ofexposure is in the adultfemale when she is ladenwith eggs. At this timeshe is more exposed thanthe shorter lived male.Both the Monarch and theViceroy enjoy freedom fromattacks by predaceous birdsand lizards at this time.On the whole, althoughthere are features of thelife of these butterflies notunde

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