. Bulletin of the Department of Agriculture. Agriculture. 16 BULLETIN 841, U, S. DEPARTMENT OF AGRTCIULTURE. these stubs were examined and a number of the inclosed larvae were found to be still living, active, and unchanged. Four months later, 17 months from the time they were gathered, they were still alive and feebly active. Infested stubs of the same grass taken during September, 1912, and treated in the same manner, contained at least one living larva on February 23, 1916, 3 years and 5 months later. The others had nearly all died within about 30 months of the time they were gathered.
. Bulletin of the Department of Agriculture. Agriculture. 16 BULLETIN 841, U, S. DEPARTMENT OF AGRTCIULTURE. these stubs were examined and a number of the inclosed larvae were found to be still living, active, and unchanged. Four months later, 17 months from the time they were gathered, they were still alive and feebly active. Infested stubs of the same grass taken during September, 1912, and treated in the same manner, contained at least one living larva on February 23, 1916, 3 years and 5 months later. The others had nearly all died within about 30 months of the time they were gathered. It is possible that the lack of necessary moisture may account for the retardation of these captives. However, the same retardation of development has been noted in the field. Inhab- ited stubs of the previous year's growth of grass and grain not infre- quently have been found, containing larvae that were to all appearances entirely normal and active. It ap- pears more than probable that in this manner the perpetuation of the spe- cies is assured in case of unfavorable seasons. During the winter the larvae are, of course, frozen, or are chilled into immobility and show no signs of life when disturbed. As soon as the earth warms in the spring they again grow active and move freely up and down within the limits of the silk-lined hibernation chamber until the time of pupation arrives. THE PUPA The pupa when first formed is riG. 11.—stems of wheat grooved internally, milk-white, slender, and somewhat longer than the larva from which it was derived. Its average length is not far from 12 mm. and its breadth is about mm. At first the pupa lies motionless within the silken pupation chamber or cocoon (fig. 12) for probably a day or two, after which inactivity it again becomes animated. When disturbed it will endeavor to escape the threatened danger by moving either up or down the tube, hitch- ing itself along in much the same manner as the larva but going a lesser distance with e
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