98 Riley Some Interrelations of Plants and 



prominence of the capital projection, to piercing the slight cov- 

 ering of the stem left ungnawed by the larva. The former is 

 very regular in its appearance as a moth at the time of the flow- 

 ering of the Yuccas in their native range. The latter appears 

 earlier, as the food of its larva is earlier ready, and the female 

 could not oviposit in the riper stem." 



Some ten species of this genus Prodoxus have been described, 

 all of them having the very same structural characteristics and 



in the adolescent states being 

 scarcely distinguishable. Pro- 

 dims decipiens is associated 

 with Pronuba yaccasella east of 

 the Rocky Mountains, and Pro- 

 f/o.o/x sordid//* is similarly as- 

 sociated with Proiinba xynthc- 

 tica, breeding in the flower 

 sterns of Yucca bremfolia. All 

 the other species are associated 



FIG. 1.3. PRODOXUS MARGINATUS : a, anal ah- with Proiinlxi iiHtCU-lata., breed- 



dominal joint of female X 26; b j o, hasal j^ e ithei' ill the base of the 

 joint of ovipositor; tj o, terminal joint do. ; . 



ov, oviduct; c, claspers of male from above Capsules Or 111 the flower Stem 



X 18; pr, front wing-hair-line showing or the maill stem of Ydrcd 



whipplei I have found Pro- 

 doxus larva? in the stems of all other Yuccas which I have been 

 able to examine, and doubtless a number of other species are 

 yet to be discovered and characterized. The species so far 

 known are interesting in that they illustrate in a remarkable 

 manner what I have 

 called fortuitous varia- 

 tion, or superficial color- 

 ational characters ; also 

 a great tendency to 

 graduate into each other 

 b y variations among 

 themselves, not only in 

 the structure of the ovi- 

 positor and the male 

 genitalia but in the wing 

 markings. The time to 

 which these remarks are <'"'""' '"iMrjr'd. 

 limited will prevent my going into descriptive details, and 



FIG. 14. PBODOXIS Y-IN\ i:i:srs: ft, left front wing, 

 hair-line, underneath showing natural si/e: l>, geni- 

 talia of male, dorsal view X 14; c, do., lateral view 

 IS: <J, anal joint of female with ovipositor ex- 

 BertecL lateral view X 2(1: c, tip of ovipositor still 



