226 BULLETIN NO. 62. 



running' lengthwise from near the base to the point of the wing, 

 this stripe being diagonally crossed by whitish lines, which, on the 

 outer margin of the wing, join a broad pale buff sub-marginal band. 

 The posterior wings have a broad rosy band across them, bordered 

 on both sides by a brownish band. The head is large, top of thorax 

 is brownish, with longitudinal white lines, and the abdomen has. 

 on the upper side, on each side of the middle, a row of black and 

 white spots. 



In its flight about flowers in the eatly morning and in the late 

 afternoon, it very much resembles a humming bird, poises in the 

 air before flowers after the manner of a humming -oird. running its 

 very long mouth parts into the flowers for the nectar. The writer 

 has been -charmed in observing this moth in the sunny afternoon 

 hours in the early part of the summer, as it sought places on which 

 to rest, the color of which harmonized with the colors on its bo ly 

 and wings. They may be seen to fly very rapidly over various 

 spots in the ground, finally selecting one and settling upon it, im- 

 mediately coming to rest. Approaching such a spot where a .-rioth 

 has been seen to alight, it is with difticulty that its position is de- 

 tected. 



One brood of the caterpillars only is believed to occur in Mon- 

 tana, the eggs for this brood being deposited in June, and the cater- 

 pillars feeding until about the middle of August. A great variation 

 in the sie of these caterpillars has been referred to above and this 

 variability may be attributed to the protracted period through which 

 the eggs are laid. 



Two distinct forms of larvae belong to this species, both of 

 which are shown in the accompanying figure. Various gradations 

 between the two may occur, but it was noticeable in our experience 

 with the species last season that these two forms here illustrated 

 very much outnumber the intergrades. The form shown at b has 

 a yellowish green background, with a prominent sub-dorsal row of 

 elliptical spots, each spot consisting of two black curved lines en- 

 closing a bright, crimson space and a pale yellow line. The spots 

 are connected by a pale yellow stripe, edged above with black. In 

 the other form the prevailing color is black but it has a narrow 

 yellow line along the back, which is very conspicuous, and a series 



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