REAUMUR 263 



wild suggestions for the advancement of science and the 

 improvement of the human race. Voltaire, who had a 

 spite against Maupertuis, avenged himself in the Diatribe 

 du Docteur AJcakia, which holds up Maupertuis, and 

 indirectly Reaumur himself, to the ridicule of mankind. 

 The reader does not soon forget the resinous varnish 

 which is to prolong our days. 



Leaf-Rollers and Leaf-Folders^ 



Reaumur has a pleasant chapter on the caterpillars 

 which roll up or double in two the leaves of plants. 

 Oak, the common fruit trees, many garden shrubs, and 

 some herbs, yield plenty of familiar examples. One 

 leaf-folder can nearly always be procured, at least in 

 summer, upon ivy, and another is plentiful on lilac in 

 June. Most leaf-rollers and leaf-folders are Tortrices, 

 Pyralids, or Tineids. 



R&umur gives a practical hint to those who desire to 

 watch with their own eyes the operations of such larvae. 

 Having got a supply of rolled or doubled leaves, take 

 fresh branches of the same plant and stick the cut ends 

 into damp soil. Then turn out the caterpillars from 

 their retreats and lay them on the leaves ; they will 

 make haste to conceal themselves in their accustomed 

 way, whatever it may be, and every detail of the work 

 can be observed. We cannot even name all the cater- 

 pillars described by Reaumur, and shall have to content 

 ourselves with his account of the tortrix of the oak, 

 which is common in early summer, sometimes so common 

 that the trees are completely stripped. 



One chief purpose of leaf-rolling is no doubt protection 

 from birds and other enemies, but the same leaf which 

 provides shelter to the larva and the chrysalis also yields 



1 Vol. II, M^m. V. 



