. Bulletin of the Department of Agriculture. Agriculture. 12 BULLETIN 766, U. S. DEPARTMENT OF Fig. 5.—Compsilura concinnata: First- stage larva, right lat- eral view. Greatly enlarged. (Original.) The larvae differ somewhat in appearance in the three stages. In the first-stage larvae the mouth-hook is single pointed, being heavily chitinized throughout with the exception of the inside areas of the divided posterior part. This posterior end is membranous and serves as a place of attachment to hold the hook in posi- tion, this being true of all three stages. The first segment
. Bulletin of the Department of Agriculture. Agriculture. 12 BULLETIN 766, U. S. DEPARTMENT OF Fig. 5.—Compsilura concinnata: First- stage larva, right lat- eral view. Greatly enlarged. (Original.) The larvae differ somewhat in appearance in the three stages. In the first-stage larvae the mouth-hook is single pointed, being heavily chitinized throughout with the exception of the inside areas of the divided posterior part. This posterior end is membranous and serves as a place of attachment to hold the hook in posi- tion, this being true of all three stages. The first segment has a row of heavy spines around its base, while the second segment is thickly studded with the same kind of spines. The ventral part of the remaining segments is also fitted with the same spiny structure, in this case the spines extending upward laterally along the anterior border of each segment. All of the seg- ments are more or less covered with what, under the high-power microscope, appear to be very small granulations. On the last abdominal seg- ment there is a peculiar set of hooks that make possible the determination of first-stage Comp- silura. These are for the purpose of attach- ment to the stigma of the host. (Fig. 5.) The second-stage larva of Compsilura differs from the first in three main points: (1) The mouth-hook is double throughout, the halves being jointed by a chitinous structure, and is jointed in one place (fig. 6) ; (2) the chitinous part of the hook extends farther basally, the whole outline of the hook being more uneven; and (3) the heavy spines on the integument are lost in this stage, while the anterior border of each ab- dominal segment has two or three rows of lighter spines, which extend com- pletely around the body. The first segment is more contracted on the ventral surface, grading off at a gradual angle to its junc- tion with the second seg- ment. The anal hooks are wanting in this stage and the permanent struc- ture of the anal stigmata is
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectagriculture, bookyear
