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Show 1887.] VALUE OF COLOUR AND MARKINGS IN INSECTS. 225 insect-eaters. Again, only one species out of the 9, viz. Nomada marshamella, always remained untouched by very hungry animals when other food was withheld ; and we can only surmise as to what would have been the results if the other 8 had been similarly tested. It is, however, quite certain that many of them would have failed. This is, indeed, proved by tbe following figures:-Out of the 37 cases 15 were exposed to this rigid test, i. e. the species in the columns under m y name in Tables I., II., and IV. (excluding S. fuciformis and C. neustria), and of the 15 only three remained untasted, and of these two have been shown by Miss Cundell to be eaten under certain circumstances. Looking at all these figures, and especially the last, we can well understand the following objection being urged against Wallace's suggestion. It may be said, the tables, indeed, show that Wallace was right in predicting that an unpleasant attribute would be found to be associated with a conspicuous appearance. That has certainly been proved by the results of a vast majority of tbe experiments ; but of what value is this association when insects are seized, tasted, and rejected in spite of the warning colours which, ex hypothesi, are assumed to prevent this very contingency ? In the first place, an answer to the objection is found in the very fact that the insects were tasted and rejected to a much greater extent when the vertebrates were thoroughly hungry, for we see that when other food is present the conspicuous insects are, as a rule, untasted. W e shall presently see that an inconspicuous but nauseous insect is approached by Lizards in a very different way from one which is conspicuous and nauseous. There was, in fact, strong evidence in the details of some of m y experiments, that the vertebrate enemies were well aware that the insects were distasteful, and yet, when exceedingly hungry, did their best, in some cases successfully, to eat them. This was especially seen in the behaviour of the Lizards towards the larvse of O. potatoria, P. bueephala, and Croesus septentrionalis in m y experiments, and towards the larvae of C neustria, A. grossulariata, and P. auriflua in Jenner Weir's experiments; for in all these cases the Lizards made repeated attempts to eat the larvse, again and again rejecting their prey with every sign of disgust (rubbing the mouth against the cage) ; and yet in the end the larvse were reluctantly eaten. I believe, however, that the suspicion with which conspicuous insects are approached results from the strongly impressed experiences of early youth and not from a habit which has become hereditary. In many cases, however, the warning experience may have been gained without tasting the insects; for we have seen "that the latter are often protected by smell, which can be perceived from a distance. Excluding these instances, however, the experience of conspicuous nauseous forms must have been gained by actual trial of a large number. I hope to be able to show that it is not necessary for the young insect-eating Vertebrate to actually make trial of every species of unpleasant-tasting insect in its locality, in order to be equipped with an efficient stock of experiences with which to conduct its later life. |