10 



The mature larvae select secluded spots in which to pass the 

 pupal stage. A few may be found transforming within the sheaths 

 of the upper leaves, but the majority go down the stem to the old 

 leaves and sheaths at the base of the stem near the surface of the 

 ground. The duration of the pupal stage varies not only in 

 the two forms of the adult but also at different seasons. In 

 the first generation in the spring it requires from two to three 

 days for the larvae to transform to the wingless adult form, and 

 from four to five days to the winged adult, but as the weather 

 becomes warmer they transform more rapidly. 



Imago. {Plate /., Figs. 3 and 4.) 

 There are two forms of the adult females, one of which possesses 

 wings, while the other has merely the rudiments in the form of 

 short pads. The description of the winged form is as follows : 

 The length varies from 1 to 1.6 mm., the average being about 

 1.32 mm. and the width of the thorax is about .28 mm. The 

 color is light yellow, with brownish or blackish markings. 



The head, which is rounded in front, is marked with transverse 

 strise and a dusky border posteriorly (Plate IV., fig. 25). The 

 antennaj (Plate IV., fig. 28), composed of eight segments, are 

 approximate, whitish at the base, gradually becoming more dusky 

 toward the apex, where they are nearly black. The sixth segment 

 has an oblique suture toward the terminal end, which gives the 

 antenna the appearance of consisting of nine segments. Segments 

 three to six are distinctly ringed with whorls of small setffi, each 

 segment bearing a number of stout spines, which are most numer- 

 ous on the last three. Some of these spines are thick and blunt, 

 rounded at the ends and slightly tapering. Unlike the other hairs, 

 they are not brownish, but are thin-walled and transparent. They 

 vary considerably in size and position, the longest one being found 

 upon the inside of the sixth segment. Upon the dorsal side of 

 the third segment and the ventral side of the fourth, two of 

 these spines appear to have united, forming a delicate crescent- 

 shaped appendage, which is attached by a short truuk to a clear, 

 membranous depression near the end of these segments. The 

 function of these structures is not known, but, as they are found 

 only upon the antennae, they are doubtless organs of sense, and 

 may be called sense cones. 



The eyes are large, and of a dark-red color. Three orange-red 

 ocelli are present, arranged in the form of a triangle with the ver- 

 tex in front, placed near together and well up on the vertex of the 

 bead between the eyes. The thorax is of a darker yellow color 

 than the rest of the body, and is marked with elongated dusky 



