I have had caterpillars spin by the hundred, in boxes containing most of these things, have gathered outdoor cocoons by the peck, and microscopically examined dozens of them, and with the exception of leaf, twig, bark, or some other foundation against which it was spun, I never have seen a cocoon with shred, filament, or particle of anything used in its composition that was not drawn from the spinning tube or internal organism of the caterpillar, with the possible exception of a few hairs from the tubercles.  I have been told by other workers that they have had captive caterpillars use earth and excrement in their cocoons.

This same work, in an article on protective colouration, lays emphasis on the statement that among pupa cases artificially fastened to different objects out of doors, “the elimination was ninety-two per cent on fences where pupae were conspicuous, as against fifty-two per cent among nettles, where they were inconspicuous.”  This statement is elaborated and commented upon as making a strong point for colourative protection through inconspicuousness.

Personally, I think the nettles did the work, regardless of colour.  I have learned to much experience afield that a patch of nettles or thistles afford splendid protection to any form of life that can survive them.  I have seen insects and nesting birds find a safety in their shelter, unknown to their kind that home elsewhere.  The test is not fair enough to be worth consideration.  If these same pupae had been as conspicuously placed as on the fence, on any edible growth, in the same location as the fence, and then left to the mercy of playing children, grazing stock, field mice, snakes, bats, birds, insects and parasites, the story of what happened to them would have been different.  I doubt very seriously if it would have proved the point those lepidopterists started out to make in these conditions, which are the only fair ones under which such an experiment could be made.

Many people mentioned in connexion with the specimens they brought me have been more than kind in helping to collect the material this volume contains; but its publication scarcely would have been possible to me had it not been for the enthusiasm of one girl who prefers not to be mentioned and the work of a seventeen-year-old boy, Raymond Miller.  He has been my sole helper in many difficult days of field work among the birds, and for the moths his interest reached such a pitch that he spent many hours afield in search of eggs, caterpillars, cocoons, and moths, when my work confined me to the cabin.  He has carried to me many of my rarest cocoons, and found in their native haunts several moths needed to complete the book.  It is to be hoped that these wonderful days afield have brought their own compensation, for kindness such as his I never can reward adequately.  The book proves my indebtedness to the Deacon and to Molly-Cotton.  I also owe thanks to Bob Burdette Black, the oldest and warmest friend of my bird work, for many fine moths and cocoons, and to Professor R. R. Rowley for the laborious task of scientifically criticizing this book and with unparalleled kindness lending a helping hand where an amateur stumbled.