THE CANADIAN ENTOMOLOGIST. 73 



THE YOUNG LARVA OF ARSENURA RICHARDSONI, DRUCE- 



BY ALPHRUS S. PACKARD, LL.D. 



The eggs of this rare species were kindly sent me from Tacubaja, 

 Mexico, by Mr. O. W. Barrett. The food-plant of the caterpillar was 

 unknown to him. Heretofore we have only had the figures of the mature 

 larva of three species of this genus, and four sketches of the caterpillar of 

 A. armida, the better known species of this interesting genus, which 

 ranges from Mexico to Brazil. The larva figured by Madam Merian, 

 Stoll, Burmeister, and by Peters, is represented as being smooth, without 

 any tubercles, horns, or hairs. The partly grown larva, when about one- 

 half grown, is drawn as having a pair of high horns on the prothoracic 

 and a longer pair on the third thoracic segment, and a caudal horn on the 

 8th segment, also a shorter median horn on the 9th abdominal segment. 

 Peters* states that this armature is retained until the last moult. He also 

 figures the caterpillar of A. aspasia, H. Sch., which has four thoracic and 

 a caudal horn ; one would infer from his brief account that this larva was 

 fully fed, since he figures the pupa, but it may be found to belong to the 

 penultimate stage. He also figures the larva of O. xanthopus, Walk. 

 The small young (in stage HI. ?) has a pair of long, slender filamental 

 metathoracic horns about half as long as the body, and a caudal filamental 

 horn of nearly the same length. The older larva has no caudal horn, but 

 retains the two thoracic appendages, which are about a quarter as long as 

 the body. He does not positively say whether this is the full-fed larva or 

 not, but the pupa (subterranean) is figured. 



We had from a study of this genus (also of Rhescyntis and Dysdse- 

 monia), referred these moths to the subfamily Agliinae, the venation being 

 similar to that of Aglia tau. And it is a matter of no little interest to find 

 that the young freshly hatched larvse, now for the first time described, is 

 somewhat similar in armature to that European genus, whose nearest 

 allies belong to the South American fauna. 



Stage I. — -Length, 4 mm. Head large and round, wider than the 

 body, and shaped as in Adelocephala. The body is rather thick, and 

 tapers somewhat to the end. The first thoracic segment is rather wide, 



*Die Heteroceren-Raupen (und Piippen) des H. T. Peters' schen manuskript- 

 werkes ; Biologische Beitia^e zur Brasilianischen Schmetterlings-fauna, Neudamm 

 (1898) — 1901. 



