50 THE CANADIAN ENTOMOLOGIST. 



ADDITIONAL NOTES ON THE LIFE-HISTORY OF ARCTIA 



PHALERATA, HARR. 



BY ARTHUR GIBSON, DIVISION OF ENTOMOLOGY, CENTRAL EXPERIMENTAL 



FAKM, OTTAWA. 



In the December number, 1900, of this journal, page 369, the writer 

 published the life-history of the above Arctian. During the past 

 summer, through the kindness of Mr. A. Kwiat, of Chicago, in forwarding 

 eggs of A. phalerata (laid 18th June), I have had the opportunity of still 

 further studying this species, and, as these larvae varied considerably from 

 those described in 1900, the following notes were made : 



In the larval stages i, ii and iii those bred in 1901 answered well to 

 my former descriptions. In stage iv the larvae were not so black as the 

 specimens reared the previous year, but many of them showed the dorsal 

 stripe. This stripe was also present in stage v, besides which 40 of the larvae 

 possessed a series of pale orange spots on sides between tubercles ii and 

 iii, and iii and iv. and the skin of the body in a line with the upper spots 

 (between tubercles ii and iii) was slightly grayish, not black like the rest 

 of the skin ; this and the spots gave the appearance of a faint lateral 

 band, distinguishable on all segments but 2 and 13. In stage v in 1900 

 none of the larvae showed the dorsal stripe. In stage vi last season all of 

 the 123 specimens, with the exception of 2, showed a distinct orange dorsal 

 stripe, but in a few specimens this was faint. In 1900 the specimens 

 did not show a dorsal stripe in this stage. In stage vii the larvae were 

 much larger the past season than those bred the previous year. The mature 

 ]arvae in July, 1900, measured 30 mm. at rest; those in July, 190 1> 

 averaged 42 mm. in length, and all the specimens but 9 showed the 

 distinct dorsal stripe, expanded in the middle of each segment, or the 

 series of elongated spots noted in my previous description of this stage. 

 In many of the larvae the stripe was present on all the segments, but was 

 particularly wide and distinct on segments 5 to 13, inclusive. 



In stage vi in 1900 the width of the head averaged from 2.0 to 2.4 

 mm. The past year some of the heads were 2.6 mm. wide. In stage vii 

 also in 1900 the width of the head, as given in my description, was 2.5 to 

 2.8 mm. In July, 1901, the widest head measured 3.4 mm. The chief 

 variation in the mature larvae bred the past season was in the colour of 

 the bristles. In many specimens the bristles from all the tubercles, with 

 the exception of a few short bristles from the tubercles above the 

 spiracles, were of a decidedly pale grayish colour, tipped with black ; in 



