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EIGHTH ANNUAL REPORT 



into two retractile subjoints of the 

 body, and may be hidden within the 

 terminal joint proper, so as to show 

 only the upper tip, or extended as in 

 the figure (Fig. 19, a). It is in reality 

 composed of two thin layers, closely 

 appressed except at the upper or 

 dorsal portion near the base, where 

 it swells into a somewhat angular 

 ridge outside and is hollow within. A 

 more careful examination will show 

 that the upper portion is irregularly 

 and obliquely striate (Fig. 19, d), the 

 striations representing folds of the 

 membrane, to facilitate expansion ; 

 and that the hind border is garnished 

 with fine hairs which easily rub off and leave the edge quite sharp, 

 so that the two layers form a blade which is admirably adapted to 

 pressing in between narrow passages, or even to splitting frail and 

 hollow stalks. In life this ovipositor plays on the two sub-joints which 

 may be greatly extended, and when so extended forms a somewhat 

 cylindrical and telescopic tube which is rendered very firm by a series 

 of stout muscles within. (Fig. 19, h). The valve opens from top to 

 bottom, and may be very considerably distended so as to make way 

 for the oviduct which is a quite complicated structure. 



AmiY Worm Moth: — a, end of abtlomen 

 denuded aud showing ovipositor at rest; b, 

 same witli ovipositor fully extended ; c, f, 

 retractile subjoints; h, eggs — all enlarged; y, 

 eggs, natural size. 



NATURAL IIISTOUY OF THE ARMY WORM. 



Up to the year 1861 our knowledge of the natural history of the 

 Army Worm had remained a blank. Nothing, indeed, of a scientific 

 nature had been published respecting it. "A few very observing 

 farmers ventured to predict its appearance during very wet summers 

 succeeding very dry ones. They did not know why this was the case, 

 but it was a lact that they had learned from experience. It was also 

 known that the worm attacked only the grasses and cereals, that it 

 was gregarious in iis habits, and that it disappeared suddenly, in a 

 manner as seemingly mysterious as that in which its advent was sup- 

 posed to have been made." 



In 1861, however, its wide spread occurrence over the country 

 and the large amount of injury it caused, attracted the attention not 

 only ot tarmers, but of several well known writers on economic ento- 

 mology and agriculture. Among these may be mentioned my late 

 friends B. D. Walsh, of Illinois, and J. Kirkpatrick, of Ohio ; and Prof. 

 Cyrus Thomas, of Illinois, Dr. Asa Fitch, of New York, and J. H. Klip- 



