98 LEAF-MINING INSECTS 



between the condition in which some segments remain un- 

 fused and mobile, and that in which the outside covering of 

 the pupa is entirely fused and soldered; for though they are 

 immobile, and though the appendages are attached to the 

 body wall and the segments are attached together, the 

 fusion is incomplete and soldering weak and the parts may 

 be split from one another more easily than in most immobile 

 pupae. They possess neither backwardly pointing spines 

 on the dorsum of the abdomen nor cutting edges on the 

 cephalic extremity. Such structures are to be associated 

 with mobility in the pupae and emergance of the pupal shell 

 before the release of the adult. The pupae of Leucoptera 

 and Proleucoptera are shorter and thicker than are those of 

 Bedellia and Lyonetia. Bedellia pupae have a long cephalic 

 projection and well-developed ridges and projections on the 

 body. 



Pupation always takes place outside the leaf in this group. 

 In other respects the members are not very uniform in 

 pupating habits. Some make cocoons and some make none. 

 The naked chrysalis of Bedellia somnulentella is held hori- 

 zontally against the under surface of the leaves, supported 

 by recurved spines upon crossing threads. Lyonetia latis- 

 trigella pupa is likewise naked and this is suspended by 

 means of a few silken threads across a bent leaf. Some 

 species prepare a delicate web on the underside of the leaf 

 which has the form of a letter H with a very broad cross 

 bar. Between this broad median band and the leaf surface 

 some species, as Leucoptera coffeella, transform to pupae 

 without forming any definite additional cocoon. Other 

 species spin cocoons between such a web and the leaf. In 

 Leucoptera pachystimella and Leucoptera albella the cocoons 

 proper are supported against the leaves or other surfaces by 

 short bands or cables. Lyonetia clerckella of Europe and 

 our native Lyonetia speculella spin cocoons which are slung 

 hammock-wise by the extremities of the cocoons themselves 

 upon the lower surface of slightly curved leaves. 



