K1I.EY NOTES ON THE YUCCA BORER. 



323 



o^a 



Notes 011 the Yucca Borer, Me gathymns yucca (Walk.) 



By Chas. V. Riley. 



'•He who. by a minute analysis of any animal, ena- 

 bles us to soli'e any dubious point connected therewith, 

 does more for the elucidation of this much abused 

 natural system than the greatest and most ingenious 

 theorist who has yet taken the subject in hand." 



Westwood. 

 [Fig- 2v] 



l&T, #> The study of aberrant forms 



in Nature is always inter- 

 esting. They are continually 

 confronting the naturalist. 

 They baffle the systematist 

 and constantly remind him of 

 the necessarily arbitrary nature 

 of his classificatory divisions. 

 Few divisions seem more na- 

 tural, at first glance, than that 

 of the Lepidoptera into Rho- 

 palocera (butterflies or day-fly- 

 ers) and Heterocera (moths or 

 night-flyers). It was no soon- 

 er proposed by Boisduval than it was recog- 

 nized as a most convenient arrangement, and 

 adopted very generally. The antennae in this 

 Order are always conspicuous, and their club- 

 bed or non-clubbed tips are easy of observa- 

 tion, and associated with other important cha- 

 racteristics which separate the two groups. 

 The Sphingidse, however, by their crepuscu- 

 lar habit and their antennae thickening toward 

 the end. though terminating abruptly in a 

 point, bring the two groups in close relation- 

 ship and diminish their value; while the 

 Castniidse on the one hand and the Hesperi- 



