OS 



Rlleu — Som.c Interrelations of Plantf^ and Insects. 



prominence of the capital i)rojection, to i)iercing the slight cov- 

 ering of the stem left ungnawed 1)}' the larva. The former is 

 very regular in its appearance as a moth at tlie 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 tliem having the ver}^ same structural characteristics and 



in the adolescent states being 

 scarcely distinguishable. Pm- 

 (Jo.rns deciplens is associated 

 with Promiha yurcasella east of 

 the Rock}" Mountains, and Pro- 

 doxus sordidus is similarly as- 

 sociated - with Pronuha synthe- 

 tica, breeding in the flower 



stems of Yiuxa hrevifolia. All 

 the other species are associated 

 Fir,. 13.— PuoDoxus MARGiNATus : a, aiiiii mi> witli Proiinha inacaluta, breed- 

 dominai joint of female -X2G; 6./ 0. basal jj^^- either in the base of the 



joint of ovipositor; < J o, terminal joint do.; "^ • i j 



ov, ovidtiot; r, claspers of male from above CapSUlcS Or ni the floWCr stCUl 



— X 18; 2^/-, front wins-hair-line .showing qj. ^hc main steiU of YnCCa 



natural size. , . , . , , ,. i t^ 



ivkqyplei. i have lound rro- 

 doxus larva3 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- 



JDOSitor and the male bair-llne underneatli sliowing natural size; 6, geni- 



genitalia but in the wing *'^"=> "'' "^f '^' •^°':*^' 7'7 " -'' '■ ^V'"' '''*''■:" "'"' 



" _ _ " — X IS; d, anal joint ot female witli ovipositor ex- 



markingS. The time to serted, lateral view - X 20: r, tip of ovipositor still 



fiirth(>r enlarsed. 



Fi(^ U.— Propo.xus y-ix\i-Ksrs: n, left front wing, 



which these remarks are 



limited will [jreveiit my going into deseriptivt' 



detail 



lid 



