DIPTERA OF MINNESOTA. 



05 



genus, D. ziolicola, found in Minnesota, rolls up violet leaves and lives 

 within. Still another, D. resinicola, or the "Resin Gnat," is found 

 living as maggots in lumps of resin on various species of pine. This 

 resin may have formed there as the result of injury by some cater-\ 

 pillar, or by abrasion of the bark; whatever its origin, it protects the 

 maggots, which undergo their transformations in it. Our box elders, 

 always a prey to insects, have been for three years or more disfigured 

 by galls on their leaves, as shown in Fig. 55. 



Fig. 53. A "skipping" Cecidomyii 

 larva, bred from Polyporus. Much 

 enlarged. Original. 



Fig. 54. The imago of the maggot shown in Fig. 53, 

 much enlarged. The cross below shows actual size 

 of insect. 



Another tiny member of this family, C. aceris, also reared in 

 our laboratory, causes a rolling of the leaves of the soft maple, in 

 which very imperfect gall lives the maggot. We also have in Minne- 

 sota, in fact, we have reared them from the galls, Cecidomyia rohiniae, 

 working on the leaves of locusts. The leaves of our basswoods too 

 frequently suffer from a Cecidomyid gall maker. We have also 

 reared specimens of a Cecidomyid from the fungus known as Poly- 

 porus. The larvae found in this fungus had the power of leaping. 



