MORPHOLOGICAL ADAPTATION IN INSECTS — GRANDI 207 



which required under the same conditions a different position; (3) 

 they have modified those which required modifications to function 

 in a particular way; (4) they have acquired new structures suitable 

 for helping the others in the work; (5) finally at a given time of 

 their postembryonic development, by changing place, activity, or 

 ways of feeding they are able to rebuild some of the organs previously 

 lost, and conversely to lose others which before were present and 

 functioning, or to be completely transformed by taking again through 

 a simple moult the classic habit of cruciform larvae, which they had 

 left, suitable, i.e., for accomplishing a kind of reversion of their onto- 

 genetical evolution even though adaptative. 



II. LARVAE OF PHYTOPHAGA COLEOPTERA 

 (BUPRESTIDAE, CHRYSOMELIDAE, CURCULIONIDAE) 



In this section I shall take into account, among the larvae of 

 Coleoptera, some that have a specialized diet, making them more 

 interesting for our purpose. 



We shall begin with a leaf-mining representative of the family 

 Buprestidae, Trachys pygmaea F., which develops within the leaves 

 of Althaea officinalis L. belonging to the mallow family. The larvae 

 of Buprestidae, as is well known, live for the most part in cases 

 within the branches or big roots of various trees and shrubs ; therefore 

 they are xylophagous and exhibit a flattened body, a very strong 

 prognathous or subprognathous head capsule, deeply enclosed by the 

 prothorax, which is rather broad and gives to the insect a clubbed 

 appearance. Ocelli and legs are absent. The modifications undergone 

 by the larva of Trachys pygmaea F. (we compare it with the larva 

 of Capnodis tenebrionis L. in order to have a reference) consist 

 mainly of a widening of the body segments and therefore the loss of 

 the clublike aspect ; the reduction of the head size in comparison with 

 the thorax; much greater enlargement of its free portion (the outer 

 part) ; the disintegration of the head, and the rather less sclerotization 

 of its inner part ; the presence of ocelli, a greater development of the 

 antennae and their supply of sensillae; a fine sculpture of the seg- 

 ments of the integument and the presence in them of ambulacral 

 areae and little sclerotized patches. All the above is obviously in 

 correlation with a microhabitat that is larger, softer, and clearer than 

 that represented by the dark, narrow, rigid, and hard-walled galleries 

 bored in the wood, and with the different feeding. The reappearance 

 of ocelli, that is, organs lost not in a stage or phase preceding the 

 larval ontogenesis, but in almost all the representatives of a family 



