494 P. W. CLAASSEN 
observations had to be discontinued. ‘The period of egg-laying is therefore 
spread over a number of weeks. 
The larva.— In the laboratory, the larvae were placed in tin salve boxes 
which had been partly filled with sterilized sand and moistened with 
boiled water. A little excavation was made at one end of a fresh piece 
of the rhizome of cat-tail, and in this the larva was placed and left to feed. 
Such pieces of rhizome, two or three inches long, remained fresh from 
three to five days. As the larva became older and needed more food, 
these pieces of rhizome had to be replaced more often. By splitting the 
plece open, excavating a little hole in the center for the larva, and then 
binding the pieces together again with rubber bands, observations could 
be made from day to day without unduly disturbing the larva. 
As soon as the larvae are hatched, they begin to bore directly into the 
stem, working toward the center, and thence downward toward the 
crown, and from there into the central axis of the rhizome (Plate 
XL, 19). Like the other borers of the cat-tail, this larva at once 
seeks the central part of the plant, where the tissue is most tender and 
succulent. However, the weevils seem to have a special preference for 
starchy food, and for this reason they work downward to the rhizome, 
the core of which is:composed mainly of starch (Plate XLV, 60). In 
rearing the larvae, it was found that they would not eat any other part 
of the rhizome except the starchy core. As many as seven larvae have 
been found in a single plant. In one instance they were all working 
at the crown and as a result had nearly cut off the plant. 
The affected plants present a somewhat stunted appearance. Some- 
times the central leaves die and the plant fails to head out. The tunneled 
rhizomes shrivel up considerably and often darken decidedly. | 
The larvae grow very rapidly, and the time from hatching to the pupal | 
stage averages about three weeks. When the larva has become fully 
grown, it prepares an oblong pupal cell in the stalkof the plant, from one 
to three inches above the ground (Plate XLVIII, 80). The pupal cell is 
made of partly masticated pieces of the stalk, with which the burrow is 
plugged above and below. In the laboratory some of the larvae pupated 
in their burrows in the rhizome, while others, that were reared in plants 
growing in flower pots, tunneled through the soil to the bottom of the pot 
and there made a smooth, oblong, unlined, earthen cell in which they trans- 
formed. The reason for their going down into the soil appeared to be a 
