250 



Arihropoda. 



Fig. 211. A Larva (maggot) 

 of a W a s p, seen from the left. 

 B Pupa of the same from 

 helow. — After Eatzebnrg. 



larrse differ extraordinarily from the adult, botli in appearance and in iaMts {e.g., 

 the Blow-flies, and many others). 



Tlie 1 a r T se of metabolous Insects occur in a number of 

 different forms. Of special modifications may be mentioned tbe 

 peculiar type occurring in tbe Lepidoptera and Tentbredinidae, specially 

 cbaraoterised by the presence^ on the ventral side of the cylindrical 

 bodyj of a number of so-called prologs, small muscular dermal 



outgrowths which play an important part 

 A B in locomotion ; such larvae are termed 



caterpillars or (in the Tenthredinidse) 

 pseudo-caterpillars. In a number 

 of larvae of different orders, legs are 

 altogether wanting; such forms, 

 termed maggots, are usually pale, blind 

 creatures, which are concealed in plants as 

 parasites, etc. ; occasionally they are more 

 motile (aquatic forms, e.g., Gnat-larvae). 

 The most degenerate occur among the 

 Blow-flies and other Diptera; these 

 are termed headless maggots, since 

 even the head is not clearly developed, 

 whilst it is very striking in many other 

 forms in consequence of its thick brown 

 cuticle. Many larv«, which lead a hidden existence in the earth, 

 ■or in cavities in wood, etc., without being maggots, i.e., without loss 

 of the thoracic limbs, have habits like those of most maggots ; they 

 are blind, or almost so, with short or feeble legs, and soft, fat bodies. 



In most holometaholoiis Insects, the body hardly changes at all during the 

 whole of larval life. In others, however, it has a difiCei-ent appearance at different 

 ages, a fact which is chiefly connected with changed habits. This is the case in 

 Meloe and its allies; the larvse hatch as small active organisms, provided with 

 legs. They crawl about on plants, and attach themselves to certain Bees, in whose 

 dwellings, after changing into maggot-like creatures, they pass the rest of their 

 larval life, feeding upon the stores of their hosts. 



The p u p se do not exhibit such a variety of form as the larvaj, 

 but here, too, there are many which are interesting to note. The 

 Lepidoptera, for instance, have a peculiar pupa (chrysalis), in which 

 the antennae, mouth-parts, legs, and wings, lie close on to the body, 

 and are hard and chitinous all over their outer surfaces, as is also the 

 Test of the body where it is not covered by these parts ; the limbs, 

 therefore, appear to adhere to the sides of the body, and it looks as 

 if they were all covered by a coat of varnish. In many of the 

 Diptera, the chitinous cuticle is considerably hardened previous to 

 pupation, and when it is later separated from the subjacent soft parts, 

 it is not as usual thrown off, but remains as a hard capsule round 

 the thin-skinned pupa, and thus serves as a protective case ; it is 

 ■only thrown off when the imago breaks through (coarctate pupa). 



