THE CANADIAN ENTOMOLOGIST. 117 



range. Still, one following the early histories of this genus must be struck 

 by their persistence in selecting a certain food-plant, and it is like going 

 by a well-blazed trail if the list be but known. 



Rigida matures at a mean date for the genus, about Sept. 15th, and 

 emerges, from the hibernated egg unquestionably, about the first of June. 

 The earlier stages were not observed, but where a larva passes its existence 

 in a limited gallery, something can be gleaned of the early procedure. The 

 newly-emerged larva bores to the centre of the stem, slightly above the 

 crown, turns downward with the gallery, preserving and keeping free the 

 original opening. It must reach the root early, else there would be a con- 

 siderable enlargement at the crown, and this has not been noticed. In 

 well-established plants a firm and entangled cluster of fleshy rootlets 

 support three or four larvae without serious detriment to their growth. 

 There being no principal taproot, the tangle is pierced to some extent 

 without regard for boring an individual section. This is especially true at 

 maturity. The larva leaves the root-clump to pupate, the boring not 

 offering advantages for the moth's escape. Of parasites, the limited obser- 

 vations only disclosed the presence of the species of He7niteles, which is 

 such a common check in this genus. Observations of the larva were 

 sufficient to determine the most important question, its position compared 

 with its allies, placing it in the section with inqucesita and others, wherein 

 the stripes are eliminated centrally, the effect of some former habit at an 

 earlier epoch. 



Penultimate stage of larva : Head normal, smooth and shining, 

 yellowish-brown ; the labrum, mandibles and ocelli touched with dark 

 brown. There is no side line nor shade connecting the ocelli with the 

 darkened edge of the shield ; setae normal ; width 22 mm. Body cylin- 

 drical, less attenuated than some, colour dull pinkish, brighter doubtless 

 in preceding stages. The dorsal and subdorsal lines rather broad, yellow- 

 ish-white, all break abruptly at, and do not cross, the first four abdominal 

 segments, where the even body-colour prevails. On the remaining 

 abdominal joints, in addition to the whitish lines, the larva becomes white 

 ventrally. On the meso- and metathorax the skin shows the usual creased 

 or puckered appearance, which becomes filled out at the final stage. 

 Cervical shield wide as head, of the same polished, corneous nature, 

 though a little lighter in colour, its lower, lateral border edged with dark 

 brown ; the usual complement of setae. Tubercles rather small for the 

 stage, not very contrasting, mostly pale brown in colour ; i and ii are 

 minute, iv and v best shown, iv is largest, the size of the spiracle. On 



