10 RIVULA SEkUCKALIS. 



growth becomes more perceptible, as it attains a 

 length of from 5 to 6 mm. 



After the fifth moult its appearance is unchanged 

 beyond the increase of growth, as it soon extends to 

 7 or 8 mm. in length. Its ravages on the grass are 

 rather conspicuous, as it goes from one leaf to another, 

 yet it is careful not to attack the extreme point or 

 the midrib, but after the sixth or last moult it feeds 

 differently, beginning at the top, head upward, and 

 eating downward through the midrib, from one edge 

 to the other, in rather an oblique direction across 

 the full breadth of the leaf ; sometimes two or three 

 leaves are thus eaten, more or less, but when its 

 appetite is nearly satisfied it eats only about three 

 parts across the truncated top edge, so as to leave a 

 portion uncut on one side, generally about half an 

 inch long. But previous to this the larva has reached 

 its full growth, the length ranging from 15 to 17 mm., 

 according to sex, as the largest proved to be female. 

 The form is cylindrical, and of moderate stoutness, 

 the head rounded, and the three hinder segments 

 slightly tapered, the anal legs extended backward ; 

 the greenish-drab coloured head with dusky dots and 

 hairs as before ; the bright green of the body is 

 deepest on the back as far down as the trachea, which 

 shows faintly through the skin as a paler thread ; the 

 belly is of a rather lighter tint of the same green ; 

 the subdorsal stripes are white, and commence on 

 the second segment, continuing of the same width 

 throughout, though drawing nearer each other as 

 they approach the thirteenth. The outer edge of 

 these is straight, but the inner edge is concave on 

 every segment, so that the green ground of the back 

 appears in a series of broad ovals, with a darker 

 green dorsal line running through them ; the seg- 

 mental folds are greenish yellow ; the round spiracles 

 are flesh-colour finely edged with blackish ; the warty 

 green glossy tubercles have each on the summit a fine 

 dusky dot bearing a longish rough hair, which when 



