88 STRUCTURE OF THE LEPIDOPTERA 



we can discern the outline of a pair of small wings, and see a 

 proboscis and a pair of long antennae. Also the six long legs of the 

 future butterfly can be traced with care. 



The abdomen is conical in form, coming to a sharp point at 

 the end. and its segments are quite distinct. 



No stranger to the metamorphoses of insects would connect 

 the present form with that of a caterpillar ; they are so very 

 unlike. And yet the time occupied in the whole change, from the 

 spinning of the carpet, does not occupy more than about thirty or 

 thirty-five hours. 



The apparent suddenness of this change is really surprising, but 

 in reality the transformation is not nearly so sudden as it appears. 

 Dissection of a caterpillar a few days before the final moult is due 

 will show that the changes are already going on. In fact, a 

 simple removal of the skin will prove that the organs of the 

 future butterfly are developing. Still, in proportion to the short 

 time occupied, the change is extremely great ; and it may reason- 

 ably be inquired, Why so great a change within so short a space of 

 time ? why is not the change continued steadily and equally 

 through the larval existence ? The reason has already been hinted 

 at. Caterpillars are living eating machines, whose office is to 

 remove excess of vegetable matter. Consequently they must have 

 their jaws and bulky digestive apparatus in full development to the 

 end. If these organs were to gradually disappear as the caterpillar 

 reaches its 11011- eating stages, it would simply be starved to death. 

 So the change from the larval to the pupal state, which we may 

 regard as the final moult of the caterpillar, is a far greater change 

 than any of the preceding ones, and occupies a proportionately 

 longer time, although it is principally confined to the last few days 

 of the caterpillar life. 



A number of caterpillars, and especially those - of the butterflies, 

 suspend themselves when about to change ; and the peculiarities of 

 the modes adopted must be left for our descriptions of species in a 

 future chapter ; but we will find room here for one more interesting 

 example, taking this time the larva of one of the commonest of the 

 Vanessas (page 166) the Small Tortoiseshell Butterfly. 



The caterpillars of this insect are gregarious when young ; and 

 if ever you meet with one, you are almost sure to be able to obtain 

 a hundred or so without much searching. But as they grow older 

 they feed singly, yet generally without straying very far from their 

 birthplace. 



