374 



FOREST ENTOMOLOGY. 



BiBio MARCi, L. (St Mark's Fly). 



This insect is known as a dung-fiy, and has never been considered 

 as a forest insect. Its connection with forestry was introduced to me 

 through Mr Thring, Boughton Kettering, who sent me samples of one- 

 year seedling ash very much eaten on the thick portions of the root. 

 The damage varied in appearance, and was therefore suggestive of 

 being the work of different insects. Mr 

 Thring kindly sent me some larvte on ash 

 seedlings. They changed into pupee near 

 the end of March, and hatched out flies 

 (fig. 347) about the beginning of May, 



'¥r ^- :^ 



Fig. 347.— Bi bio uiarci. 

 a, females ; h, males. 



Fig. 348.— .1 three ■year-old sprnee injure 

 hji larcir o/Bibio marci in niirscry line. 



which Avere identified by Eev. W. J. Wingate, Bishop Auckland, as 

 B/Mo marci. Judeich and Nitsche say they are not of much import- 

 ance in forestry ; but the roots in question were very much injured, 

 and Mr Theobald informs me that they are often very injurious to 

 the roots of hop and other plants. Fig. 348 shows the injuries done 

 to a young spruce by the larvae of this fly. 



BiBIO JOHANNIS, L. 



On 11th May 1911, Mr J. P. Eobertson, forester, Chatsworth, 

 Derbyshire, sent me a sample of two-year larch seedlings which 

 were being destroyed by larvfe in the soil. The roots of the seed- 

 lings were entirely eaten up, and altogether about 50,000 larch 



