. Annual report of the Agricultural Experiment Station. Cornell University. Agricultural Experiment Station; Agriculture -- New York (State). The Pear Tree Pstlla. 233 Although the indications of the presence of some enemy is thus so conspicious, the depredator is an insect so small as to be easily overlooked. The Appearance of the Insect. The immature insect. Figs. 1 and 2.— These curious minute, oval, immature forms are called nymphs. When first hatched they are of a translucent yellow color, and hardly visible to the unaided eye; eighty of them placed end to end would scarcely measure an in
. Annual report of the Agricultural Experiment Station. Cornell University. Agricultural Experiment Station; Agriculture -- New York (State). The Pear Tree Pstlla. 233 Although the indications of the presence of some enemy is thus so conspicious, the depredator is an insect so small as to be easily overlooked. The Appearance of the Insect. The immature insect. Figs. 1 and 2.— These curious minute, oval, immature forms are called nymphs. When first hatched they are of a translucent yellow color, and hardly visible to the unaided eye; eighty of them placed end to end would scarcely measure an inch. They increase in size quite rapidly and undergo gradual changes in color and form until they measure .055 of an inch in length and .045 of an inch in diameter; the natural size is indicated by the hair line at the right of the figures. These. W Figure 2.— Full grown nymph, ventral view; a, anus; b, beak. fuU grown nymphs are oval in ehape, and of a general blackish color often tinged with red; the eyes are of a bright crimson color. A very conspicious feature is the large black wing pads on each side of the body. The whole body is very much flattened, being only one-fifth as thick as long. The adult insect. Fig 3.— From the full-grown nymph, the change is to the adult insect. In this foim th*.^ pest strikingly resembles a Cicada or Dog-day-Harvest-fly in minature. It would take nine or ten of them placed end to end and about forty placed side by side to measure an inch; the hair line beside the figure indicates the natural size of an adult. From the wide blunt head, the body tapers considerably to the sexual organs at the 30. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Cornell University. Agricultural Experiment Station. Ithaca, N. Y. : The University
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