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EIGHTH ANNUAL REPORT 



where the sides naturally roll up and afford a safe retreat. It then gradually works to 

 the base, feeding the while and rolling and shriveling the blade as it descends. Other 

 blades are often joined, and, in fact, the insect lives among the blades till it is about 



[Fig. 51.] 



Megathymus YucCJE-.—a, e£fg, side view, enlarged; 6, egg from which the larva has hatched; 

 bb, 666, uiihatohed eggs, natural size; c, newly-hatched larva, enlarged; cc, lull-grown larva, natural 

 size; d, underside ol head of same, enlarged to show the trophi. 



one-fourth grown, and seldom enters the trunk before that time. How soon, in the 

 larval development the white powdery secretion already spoken of appears, or how 

 many larval molts occur, has not been ascertained ; but the more mature larva 

 is always more or less covered with this powdery matter, which doubtless serves 

 as a protection from the mucilaginous liquid which the tissues of the i'uccas 

 contain and freelj'^ exude upon interference or maceration. Pupation does not take 

 place till the subsequent late Winter or Spring; there beinsr, from all that I can 

 ascertain, but one brood each year. The burrow often extends two or more feet below 

 ground, and during the coldest weather the larva probably remains in a partially dor- 

 mant state at the bottom. Occasionally two larvre inhabit the same trunk, in which 

 case their tunnelings are kept separate, side by side. The pupa state (Fig. 52) is gen- 

 erally assumed just below the chimney-like funnel at the top of the burrow, and no 

 other preparation is made for it than partial closing, near head and tail, to insure sus- 

 pension. This funnel is, in reality, built and extended bj' the larva, and what little 

 [Fig 52 ] matter besides silk goes to make its exterior has been added and 

 worked in from the outside. In the several larvjc that I have had 

 feeding in breeding cages, this habit of building up and making tubes, 

 for which remnants of leaves and other extraneous substances are 

 pressed into use, struck me as quite characteristic; and in one in- 

 stance I have had such a tube extended over nine inches fi'om the tun- 

 neled trunk, the moss on which the section of Yucca rested being 

 used in its construction. 



In the issuing of the imago the pupa skin is rent on the middle of 

 the notura and across the eyes, and the casings of the legs are never, 

 and those of the antennae seldom, severed from their solderings in 

 the exuvium. 



The imago rests (Fig. ')'3) with its antenn;i3, slightly diverging and 

 Megatifymus vuc- „ ,. , ^ , .,, ,, . , . i , i 



CJE :-Pupa. generally du-ected forwards ; with the wings elevated, closely ap- 



