PLANT-EATING INSECTS AND MYRIAPODS 215 



that by means of hook -like hairs can be connected with its 

 fellow so as to form a conducting structure, the length of 

 which is said to reach as much as 10 inches in extreme cases. 

 When not in use the proboscis is kept rolled up on the under 

 side of the head. All the other mouth-parts are in a reduced 

 state, the mandibles, for example, being very minute or perhaps 

 even absent altogether, a state of things markedly in contrast to 

 the larval condition. 



It is unnecessary for the present purpose to give further 

 details regarding the feeding-habits of Lepidoptera, though it 

 may be noted in passing that the caterpillars of particular species 

 are often dependent upon one or a few sorts of plant. The 

 caterpillars of the Small Tortoiseshell Butterfly (Vanessa urticcs) 

 and the Peacock Butterfly {V. 16), for example, feed upon the 

 nettle. That a female moth or butterfly should lay her eggs 

 upon the right sort of plant, quite unlike her own food, is one of 

 the most remarkable phenomena in the whole realm of natural 

 history. 



FLIES (Diptera) (see fig. 90) 



It has already been explained that the Two-winged Flies 

 which constitute this order possess a suctorial and, it may be, 

 piercing proboscis, very different in structure from that of a 

 moth or butterfly. The tube is composed of the labrum or 

 upper-lip, which is concave on its under side, and the lower-lip 

 (labium), which is concave on its upper side and is usually regarded 

 as formed by the fusion of the second maxilla. The mandibles 

 and first maxilltz are piercing stylets, by means of which female 

 gnats, mosquitoes, midges, and the like penetrate the skin of 

 their victims (p. 121). The males of most of these blood-sucking 

 forms are believed to sustain themselves on plant-juices, and the 

 piercing parts of their proboscis , are not so strongly developed 

 as in the female. The larvae of gnats and mosquitoes are little 

 wriggling worm -like creatures, living in stagnant water, and 

 subsisting chiefly upon decaying vegetable matter. 



Strongly contrasting in habit with the preceding forms are 

 the Crane-Flies (species of Tipulce), familiarly known as "daddy- 

 long-legs", which, although their mouth -parts are constructed on 

 the same plan as in the blood-suckers, live on the juices of flowers 

 and the like. The larvae, popularly called "leather-jackets", are 



