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Show 1887.] VALUE OF COLOUR AND MARKINGS IN INSECTS. 241 chiefly relied upon this species for the evidence that hunger will Vertebrate to eat an insect which is evidently distasteful to it. Further the L. viridis being less used for this purpose, were not pressed by hunger to tbe same extent as L. muralis. I think that the almost certain explanation is that L. muralis was afraid to touch an insect which was not far from its own size, while L. viridis was less timid, the difference in size being far greater. And such an explanation throws light on the cases already discussed, in which a large caterpillar is protected by gaining some marking which suggests the appearance of a serpent. On this point Weismann says (Meldola's translation as above, p. 3 3 0 ) : - " It does not require much imagination to see in such a caterpillar an alarming monster with fiery eyes, especially if we consider the size which it must appear to an enemy such as a lizard or small bird." The case of S. ligustri enforces this last remark, and shows how size alone may be efficient as a protection against the smaller insect-eating Vertebrates. So far as I am aware, this important use of size, unaccompanied by any accessory markings or any special attitude, is now brought forward for the first time ; but it is an advantage which is probably far from uncommon, considering the number of large species in the same position as S. ligustri, and it has doubtless been of special importance as an initial stage in the development of the more elaborated forms of terrifying appearance already described. Larva of Mania typica.-In this case it was perfectly clear that the larva possessed a very unpleasant taste, so that it was refused by L. muralis even when very hungry. And yet the description given in the table shows that the species is highly protected in the larval state by protective colouring and habits which correspond. As the exception is so important, I will add a few details to the proofs given in the table. Newman gives the following facts about the young lame : when hatched from the eggs laid upon the leaves of pear, plum, & c , the larvae " devour the upper cuticle and parenchyma of the leaf, leaving the lower cuticle entire, dry and brown ; they lie closely packed side by side and apparently motionless," but in reality gradually moving onwards, " leaving a larger brown space behind." W e see here a most interesting adaptation of the surroundings to the brown colour of the larva. A brown larva is conspicuous on a green leaf, and a single larva could not eat away the cuticle so as to surround itself with a brown area of sufficient size until after the lapse of considerable time. Hence the subordination of gregarious habits to ends which are tbe exact opposite of those usually sought, viz. the intensification of warning colours. We have therefore a most elaborate and perfect mode of concealment in the younger stages of larval life. It is obvious, however, that such a method can only be successfully adopted while the larvae are very small, so that a large number of them can rest for a long time on a single leaf. Accordingly Newman tells us that "in a few days, perhaps from ten to fifteen, they abandon this arboreal life," and descending, feed upon many kinds of low-growing plants. It hybernates in October, and again feeds greedily in the following spring ; but, |