knowledge is very limited, Riley's article being almost the only one 

 in which we find any definite statements concerning the early stages. 



The egg of yuccac, according to Riley, is smooth, subconical, 

 somewhat broader than high, with a slight central micropylar depres- 

 sion. Wright states (Butt. West Coast, 255) that the Megathymid 

 egg is pitted. Blasquez says of the egg of hcsperiaris that it is in the 

 form of a truncate cone with an apical depression. It is evident that 

 it shows considerable resemblance to the Urbicoline (Pamphiline) egg 

 as described and figured by Tutt (Brit. Butt. p. 85, PI. I, fig. 3, 4). 



The larva, as far as is known, is largely endophytous, living in 

 the stems and roots of various species of Yucca and Agave. This is 

 evidently an acquired characteristic ; the young larvae, according to 

 Riley (1. c. 327), spin for themselves silken tubes between the young 

 tender shoots, exactly as we commonly find among the Urbicolids 

 (Hesperiids) ; it is only in the more advanced stages that they com- 

 mence burrowing into the stem and root; such an acquired habit may 

 possibly be accounted for by the hot dry nature of the climate in the 

 country where the Megathymids are found ; the stem and root would 

 give more shelter from the extremely powerful rays of the sun, as 

 well as providing a more succulent form of nourishment. The larva 

 shows considerable variation from the accepted type of Hesperiid 

 larva, with large head and constricted neck-like prothorax; this is 

 largely due we imagine to the new mode of life — the young larvae 

 still show traces of the large head, to judge by Riley's figure, but in 

 the mature larva the head is small with very strong mouth parts, and 

 the prothorax is not constricted ; the general color, like that of most 

 stem and root borers, is dull white. In two points the manifest 

 Hesperiid nature of the larvae is, however, obvious; we refer to (i) 

 the arrangement of hooks on the prolegs and (2) the powdery secre- 

 tion developed in the last stage. According to Tutt (1. c. page 86) a 

 very characteristic feature of all Hesperiid larvae is to be found in 

 the arrangement of the hooks on the prolegs ; he says in this connec- 

 tion : "In other butterfly larvae the hooks exist, as in the Macrohe- 

 terocera, only along the inner margin of the originally circular pad. 

 In the Urbicolids the circle of hooks usually remains in the adult larvae 

 as in the Microheterocera. In some species there is a simple circle, 

 or rather oval, with a gap on the inner side ; but in many of the species, 

 chiefly among the Urbicolids {comma, sylvanus, etc.) , there is a com- 

 plete circle repeated in three rows, the outer row having the smallest 



