20 ARKIV FÖR ZOOLOGI. BAND (>. N:0 7. 



Comparison between the larvae with regards to 

 their adaption for mining purpose. 



The larvae are very interesting from the point of view 

 of their adaption to their pecuhar mode af Ufe. 



This may briefly be characterized as foUows : They pass 

 their life until they hatch completely protected between the 

 upper and lower epidermis of the leaves, without any com- 

 manication either with other larvae or with the outer world. 

 As Réaumur says «ils vivent dans une grand sohtude.» 



Their attacks on the parenchyma serves the double pur- 

 pose, to procure food and to make a path. They never de- 

 tach any portion of the parenchyma, iinless they intend to 

 eat it. 



Their adaptions may conveniently be divided into two 

 groups viz: 



a) For feeding purpose 



b) for locomotion. 



But, as above stated, no real Umit exists between the two. 



• a. Adaptions for locomotion. 



The shape of the body. In O. populi, which Hves in blotch 

 mines, where the space is much more hmited than in the 

 mines of the other two species, and the room is not so lofty, 

 the body is dorsoventrally flattened, whereas in the other 

 two species it is highly arched. In O. populi, which does 

 not form any gallery, the cuticle is much less amply provided 

 with cuticular spinule than in the two other species. Further- 

 more, in O. populi, the lateral intersegmental constrictions 

 are deep; this obviously serves the purpose to enable the 

 larva to bend the body far sideways. 



In O. fagi and O. querciis on the other hand, the I — VII 

 abdominal segments are very highly arched, with dcQp dor- 

 sal intersegmental constrictions, so that on side view each 

 of these segments appears to have an high conical projection. 



These projections, which are a httle more pointed in 

 O. fagi than in O. quercus, evidently serve locomotorial pur- 



