20 STRUCTUBE OF THE LEPIDOPTERA 



stractuve. The first point that strikes oar notice is the division of 

 its body into segments or rings, separated from each other by a 

 more or less distinct Hne or shght constriction of the body. 



There are tliirteen of these segments, reckoning, as is usual, the 

 head as the first. 



The head is usually very hard, and often of a much darker 

 colour than the rest of the body. It is also frequently divided into 

 two lobes by a couple of oblique lines, between which the parts of 

 the mouth are situated. The two powerful horizontal jaws, to 

 which we have already referred, are very hard and sharp, and 

 curved like a sickle, and therefore splendidly adapted for biting from 

 the edges of leaves. The head is also provided with a pair of 

 antennse, usually very short and inconspicuous and protected by a 

 horny covering. 



Unlike the perfect insect, the caterpillar has no large compound 

 eyes, but twelve very small simple eyes, situated on the cheeks, 



very near the mouth — six on each 

 side. 



If you examine them with a mag- 

 nifier, you see that each one is pro- 



-r. in rn n x,„^^t,t, ^x, vidcd witli a Small and very convex 

 Fig. 19. — The Caterpillak of , ,. t r 



THE Angle Shades Moth lens— a lens of very s/iori^/ociis, siich 

 'Meticulosa). as would be used for the examination 



of small objects held very near to 

 the eye. From this arrangement we should be inclined to con- 

 clude that the caterpillar can see only those objects that are 

 close to its mouth ; and this idea is strengthened if you place 

 one in a box containing a number of leaves, one of which is 

 that of its own food plant. It will wander about the box, appa- 

 rently loolcing at everv' part of every leaf it passes, after the 

 manner of a very short-sighted individual, and never taking a 

 general look round. A buttertlv or a moth can see a flower in 

 the distance, for it flies unhesitatingly from one to another in 

 the straightest and shortest path, but if you place a caterpillar 

 in the centre of a ring composed of a leaf of its food plant and 

 nine others from other plants, the chances are (nine to one) that it 

 will not walk towards what it would like to have. 



Again, the eyes are situated on the loiver part of the check, 

 directed slightly downward, and are therefore adapted for seeing 

 what is just under its jaws as it walks along. Had we no knowledge 

 whatever of the caterpillar's twelve little eyes, we should probably 



