RILEY NOTES ON THE YUCCA BORER. 325 



very generally indulged, even by those who a few years back 

 were more inclined to ridicule than accept Darwinian doctrine. 

 Shall we then say that the old divisions must be discarded be- 

 cause not absolute ? As well might we argue for the abolition of 

 the four seasons because they differ with the latitude, or because 

 they gradually blend into each other ! Entomologists will always 

 speak of moths and butterflies, howsoever arbitrary the groups 

 may come to be looked upon, or however numerous the interme- 

 diate gradations. 



These thoughts naturally present themselves in considering so 

 osculant a species as the Yucca Borer. 



BIOLOGICAL. 



The reader of these Transactions is aware that the queenly 

 Yuccas cradle and nourish a very curious and anomalous Lepi- 

 dopteron — the Pronuba yuccasella* (cf. pp. 55-64 and 178-80). 

 The genus is further interesting, from the entomological side, as 

 giving us the insect under consideration. 



* P. C. Zeller (Beitr. zur Kenntniss d. nord-amerikanischen Nachfalter; dritte Abtheil, 

 pp. 134-6, Wien, 1875) shows that his Tegeticula alba, described in )S73 from the male only 

 as a Hyponomeutid. is nothing but Pronuba yuccasella. He also condenses my account of 

 its habits and offers some remarks which I deem it proper to notice. I. Of the specific name, 

 he observes in a note, " Yielleicht mit einer kleinen Abanderung in Tucceeella, da Yucca- 

 sella eine gegen die Regeln der lateinisclien Wortbildung streitende Ableitung von Yucca 

 ist." The pedantry is perhaps excusable in so venerable and careful an author, though it 

 required little grace to see that I purposely deviated from grammatical usage; for in 

 nomenclature I prefer euphony to strict classical construction where the latter gives us 

 unpronounceable names. 2. "Die Raupe ist ohne Bauchfiisse und Nachschieber(?)" The 

 question raised here is, perhaps, also excusable, since the want of anal prolegs is so anoma- 

 lous in Lepidopterous larva?. Nevertheless Pronuba in this respect, as in many others, is 

 anomalous. The larva has no anal legs, there being not the faintest sign of hooklets ; and 

 my description was so detailed that Prof. Zeller might have omitted his query 3. Speaking 

 of the 9, he remarks: "Das Merkwiirdigste an dem Ex. ist der grosse, hellgelbe, wachs- 

 ahnliche, anscheinend solide, nicht aus Kornchen zusammengesetzte Klumpen, welcher 

 zwischen der Wurzel des Saugrii-;sels und den Vorderhiiften fest angeklebt ist. * * * 

 DieErkliirung welche Riley von der Ansammlung der Fig. 74 richtig dargestellten Pollen, 

 masse gibt will mir nicht geniigen, da ich die Maxillartaster nicht fur brauchbar zu dem 

 Zweck halte. Der kraftige SaugrUssel scheint mir dazu allein brauchbar; aber wie durch 

 allmaliges Ansammeln des Staubes eine solide, wie zusammen geschmolzene Masse ent- 

 steht, bleibt noch genauer zu untersuchen. Meines Erachtens hat Riley bei seiner hochst 

 interessanten Entdeckung noch nicht Alles gesehen, und noch andere Beobachter werden 

 erforderlich sein, urn die sonderbaren Vorgjinge bei der Fortprlanzung der Motte ganz 

 geniigend zu erklaren." I remember very well the £ specimen which Prof. Zeller had 

 under his eye, and which was received' from Mr. A R Grote, to whom I had given it. She 

 had already partly used her ball of pollen before being captured by me, and by repeated 

 rubbing in the stigma and soaking in its nect ir the mass had become welded and compacted. 

 A little soaking in pure water would have resolved and separated the grains. A more 

 careful reading of my articles on this insect would also have greatly helped Prof. Zeller's 

 comprehension; for I have shown (6th Mo. Ent. Rep., p. 133) that the pollen is collected 



