376 DIPTERA. 



larva descends to the ground and moults there. Harris states 

 that "it is shorter, somewhat flattened, and more obtuse 

 than before, and is of a deeper yellow color, with an oblong 

 greenish spot in the middle of the body. In this state, which is 

 intermediate between the larva and pupa states, which has by 

 Dr. Fitch been termed the "embryo-pupa," and by us "semi- 

 pupa," the insect spins a minute earthen cocoon, which, ac- 

 cording to Dr. Fitch, is smaller than a mustai'd seed and 

 remains in the ground through the winter, burrowing to the 

 depth of an inch beneath the surface. In the next June 



they are transformed to pupae, 

 with the limbs free. When about 

 to assume the adult state the 

 pupa works its wa}^ to the surface 

 in June and July. Its chief para- 

 site, the Plat3'gaster error Fitch 

 (Fig. 135), is allied to P. tipulae, 

 which in Europe destroys great 

 numbers of the midge. 



It is evident that deep plough- 

 ing in the fall or sprjng will destroj'' many of the insects, and 

 grain sown after the loth or 20th of Ma}^, in New England, 

 will generally escape their attacks. 



The wings of the Hessian-fly are blackish ; those of the C. 

 tritici are transparent. This last species is orange colored, with 

 long, slender, pale yellow legs, and the joints of the antennae 

 are twenty-four in number in the male, and twelve in the fe- 

 male. 



The Cecidoniyia rigidce Osten Sacken (C. salicis Fitch) forms 

 a gall surrounded by the dry and brittle terminal bud at the 

 end of the twigs of the willow. The single larva discloses the 

 fl}^ early in the spring. The bright j^ellow larA^a of C. grossu- 

 laricB Fitch, causes the gooseberry to turn red prematurel}' and 

 become putrid. The pupa of G. pini-inopis is supposed by 

 Osten Sacken to be coarctate, the larva fastening itself to a 

 pine leaf and remaining motionless until the resinous exuda- 

 tion resulting from its attacks hardens, forming a cocoon-like 

 pupa case or puparium. 



]Mr. Walsh describes in the "American Entomologist," vol. i, 



