DAY- FLYING MOTHS. 193 



but the full-grown larva is always covered with it more 

 or less copiously, and doubtless it protects the invader 

 against the mucilaginous liquor which the yucca freely 

 exudes on maceration. How many larval moults occur 

 has not been ascertained, but the insect continues in 

 larva till subsequent late winter or spring, and during 

 the coldest weather probably lies in a semi-torpid con- 

 dition at the bottom of the burrow. 



The funnel-like tube outside the burrow, made by 

 the twisting and webbing together of the tender leaves 

 when partially devoured, is quite characteristic of the 

 larva of Yuccse. The tube is, indeed, built and extended 

 often several inches beyond the trunk or stem. From 

 it the builder, especially when young, emerges to feed, 

 and the small amount of matter besides silk used in 

 its construction — the remnants of leaves and such-like 

 substances — have been obtained and worked into the 

 exterior from the outside. Pupation generally takes 

 place at the top of the burrow, just below the funnel- 

 like projection, but without the preparation of a well- 

 formed cocoon. The pupa is of a brown-black, turning 

 paler on the abdomen ; all its members are distinctly 

 defined, and, like the mature larva, it is more or less 

 densely covered with a white powdery bloom. In due 

 time the pupa skin is rent, and the imago issues. 



