871 



There is niuch yet to Ie;ini ol" the poiliiiatioii of otlier sj^eeies of Yucca, 

 and I am i»aiti('ulaily anxious to obtain the insects wliich will doubtless 

 be found associated with them. The Kegal Tree Yucca, Yucca Jilifera, 

 of northeastern Mexico, reaching a height of 50 feet, M'ith its pendulous 

 panicles 5 or G feet long, has a very elongate pistil and comi)aratively 

 short stamens. The few pods which I have been able to examine indi- 

 cate the presence of a Pronuba and doubtless of a distinct species 

 which will prove very interesting. Yucca baccata, Y. treculiana, and 

 all the species which are sufficiently distinctive in character and in 

 range may be expected to have special Pronubas associated with them. 



THE BOGX'S YUCCA MOTH. 



An interesting fact connected with Pronuba and Yucca pollination is 



that there is always associated with Pronuba yuccaaeUa another moth, 



which bears such a remarkable superficial 



resemblance to it, though possessing no 



power of pollination, that it has caused 



much confusion in the past on the part qf 



careless observers and led to a good deal 



of misstatement and error. This is what I 



have called the Bogus Yucca Moth, Pro- 



doxus decipiens (Fig. 69). In size it is 



somewhat smaller, on the average, than 



Pronuba, and, wlule found associated with 



it, appears rather earlier. The female has no maxillary tentacle, but 



otherwise the genus has all the 

 characteristics which would 

 place it in the same family as 

 Pronuba. The ovipositor is a 

 stronger instrument (Fig. 70), 

 but structurally homologous. 

 The eggs are thrust into the 

 stem while yet tender; they are 

 elongate in form, but short and 

 rounded at both ends, resem- 

 bling the undeveloped ova in 

 the ovaries of Pronuba. The 

 larva is absolutely apodous (Fig. 

 71«), forms its cocoons within 

 the stem, and transforms the 



ensuing year to a chrysalis, which has a much stronger capitate spine, 



but the barest trace of dorsal spines on the abdominal joints. It issues 



partly from the stem in giving out the moth. As I have elsewhere 



remarked : 



Who, studying these two species iu all their characters and bearing, can fail to 

 concluile that, notwithstaDding the essential differences which distinguish them not 



Fig. 69.— Prodoxcs decipiens : a, 

 imago, wiugs closed ; b. female 

 imago, wings expanded— natural 

 size; f, enlarged maxillary palpus 

 with its basal tubercle. 



Fig. 70.— Genital chakacters of Pkodoxus deci- 

 piens: a, tip of ? abdomen rendered somewhat 

 transparent; 6, basal joint of ovipositor; c, its 

 sculpture; d, terminal joint of same, its tip more 

 enlarged; /, genitalia of cf from side; </, do. from 

 above; h, egg. 



