CECIDOMYIA. 1 85 



completed." The peculiarity of this process is, that the transforma- 

 tion is undergone without shedding the larva skin, and, as the same 

 observation has been repeated by Dr. Harris on the larvae of C. 

 destructor Say and G. tritici Kirby, it is very probable that it ap- 

 plies to all the larvae of the genus. I do not find this fact men- 

 tioned in the European authors. 



Instead of a cocoon, the pupa of Cec. destructor Say is inclosed 

 in an oblong, brown case, which is nothing but its own hardened 

 pupa-skin. "The larva of this insect, says Dr. Harris (I. c.), when 

 it has come to its growth, remains fixed and motionless on the 

 culm of the wheat. Its body contracts and soon takes the form 

 and color of a flax-seed. While this change is going on externally, 

 the body of the insect gradually cleaves from its outer dry and 

 brownish skin. When this is carefully opened, the included insect 

 will be seen to be still in the larva state. It does not change its 

 condition until a few days before it discloses the winged insect," 

 etc. 



Cecid. graminicola Kalt. and another Cecidomyia, mentioned by 

 Dr. Fitch as forming an imbricated gall on Agrostis lateriflora, 

 undergo a similar kind of transformation, their pupae being inclosed 

 in the dry larva-skin. 



However different the mode of transformation of Cecid. pini 

 Deg., C. pini maritimce Duf. , and Cec. pini inopis 0. S. may ap- 

 pear, the pupoa, of which are inclosed within a cocoon of resin, it 

 is in perfect analogy with the preceding instances. The process 

 by which the cocoon is formed is exactly the same as that described 

 above by Dr. Harris. The larva of the American species C. pini 

 inopis 0. S. observed by me in the environs of Washington, fastens 

 itself to a pine leaf and remains motionless until the resinous sub- 

 stance which it exudes abundantly, begins to harden ; the larva 

 then gradually frees itself from the contact of the cocoon-like case 

 thus formed. It is very probable that this cocoon is nothing but 

 the outer larva-skin, saturated with resin. 



The pupae of Cecidomyice show a close resemblance to those of 

 the Tipvlce fungicolce, especially those of Sciara. As in the latter 

 genus, the bases of the antennas are often produced in points ; 

 these frontal projections are sometimes long, approximated, and 

 resemble horns (Cec. sarothamni, see Winnertz, 1. c. Tab. I, f. 6, 

 or Cec. verbasci Dufour, Ann. Sc. Nat., 3e se'r., Yol. IY, p. 5-24, 

 with figures, 1845); in other cases they are smaller and at some 



