170 MAINE AGRICULTURAL EXPERIMENT STATION. 1904. 



Larva. 



The footless maggot is opaque whitish, with a greenish or 

 more often a yellowish tint. It measures from 7 to 8 mm. in 

 length and is 2 mm. or sightly less in breadth. The body is com- 

 posed of fourteen segments, the ninth, tenth and eleventh being 

 the thickest. From the ninth segment the body slopes anteriorly 

 to the pointed retractile head segments. The posterior end is 

 much broader than the anterior and is squarely cut off. 



The head end is easily distinguished both on account of its 

 pointed shape and the presence of the dark chitinous jaws, which 

 are hook shaped and serve to dig the tunnels and soften the pulp 

 about the larva. The three anterior segments may be retracted, 

 hiding the hooks. See Fig. 31. 



The tracheal system is well developed. Anteriorly there are 

 two ventrodorsal tubercles between the third and fourth seg- 

 ments, the cephalic spiracles. Leading from each of these to a 

 caudal spiracle on the fourteenth segment is a lateral tracheal 

 tube. Between the fourth and fifth segments and the eleventh 

 and twelfth segments, the lateral tracheae are connected by 

 branch tubes. 



Pupa. 



In this stage the insect is pale yellowish brown in color and 

 oval in shape. It measures about 4.2 to 5.2 mm. in length and is 

 about half as broad. The pupa remains within the larval skin, 

 which becomes thicker and darker. The pupae are variable in 

 size, the larger ones being quite possibly the females. Fig. 32. 



Fly (female). 



The adult female is about 5.8 mm. in length with a wing 

 expanse of 12.15 mm. The head is light brown or pale rusty 

 red. The prominent eyes are green with reddish and steel-blue 

 reflections. The antennae are three jointed, the proximal joint 

 being shortest; the second having numerous short thick black 

 bristles on the inner face; and the distal joint long, rounded at 

 the tip. The mouth parts are pale yellow. The thorax is black, 

 striped with silverv longitudinal lines, and marked with a dorsal 

 white spot. The wings are broad and clear at the base. Four 

 dark cross bands traverse each wing. The margin of the wing 

 is armed with bristles. The legs are yellowish and black, and 



