432 



LEPIDOPTERA 



CHAP. 



The family Prodoxidae consists of some Tineids, the larvae of 

 which feed in the pods and stems of the Yuccas of south-western 

 North America ; they have the mouth of very unusual form 



(Fig. 208, E), and 

 some of them, by 

 aid of this peculiar 

 mouth, exhibit a 

 remarkable modifi- 

 cation of instinct. 

 The facts are chiefly 

 known from the 

 observations of 

 Riley l on Pronuba 

 yuccasella, a moth 

 living on Yucca 

 filamentosa ; this 

 plant has been in- 

 troduced into our 

 gardens in this 

 country, where it 

 never, we believe, 

 produces seed. The 

 Yuccas are % not 

 fitted for self-fertil- 

 isation or for fer- 

 tilisation by Insect 

 agency of an ordi- 

 nary kind. The 

 progeny of the 

 moth develops in 



FIG. 208. Pronuba syntketica. North America. A, Larva ; .1 -rWlo nf 1-1 



B, C, pnpa, ventral and lateral aspects ; D, female moth ; L 



E, head and part of thorax of the female moth : a, plant, and as these 

 labial palp ; b, maxillary tentacle ; c, maxillary palp ; , , -i 



d, proboscis ; e, base of front leg. (After Riley.) Cannot grow until 



the flowers have 



been fertilised, the moth has the habit of fertilising the flowers 

 at the time she lays her egg in the part that is to develop into 

 the pod, and to be the food for her own progeny. The female 

 moth first visits the stamens, and collects, by the aid of the 



1 " The Yucca moth and Yucca Pollination," Hep. Missouri Botanical Garden, 

 1892, pp. 99-158. 



