14 



ARKIV FÖR ZOOLOGI. BAND 6. N:0 7, 



Biology. 



The biology of O. fagi is well known, and I have nothing 

 to add to previous observations except with regard to the 

 formation of the cocoon, which will be described together 

 with t hat of O. quercus. 



The accompaning photo, text-fig. 5, shows plainly how 

 the narrow gallery starts on the median nervule and winds 

 parallel to a side nervule towards the edge of the leaf, where 

 it widens to a large blotch on the form of which the side 



Fig. 



5. Brancli of beeeh, on which 3 leaves are attacked by O. fagi. 

 Nat. size. 



nervules seem to have some influence (comp. the two leaves 

 a t the right). The parenchyma in the gallery, as well as in 

 the blotches, is entirely consumed. In the figure two cocoons 

 are plainly visible. The 3rd leaf has been attacked by two 

 larvse, which seldom occurs. 



Parasites of O. fagi. 



In spite of careful researches I was only able to find 

 very few parasites of the larvse. 



