11G THIRD ANNUAL REPORT OF 



species and by parasites,* and because such continued increase of one 

 species is inconsistent with the harmony we find everywhere in Na- 

 ture. But we may not venture beyond the inference, as the happen- 

 ings of the future are not for mortals to know. Some persons may 

 also be curious to learn why this worm increases so much more in 

 late summer and fall than in spring, since there are so many broods 

 during; the year ; or why it is only noticed in certain years ? Such ques- 

 tions, likewise, can receive no definite answer, 



" Till old experience Jo attain 

 To something- like prophetic strain." 



For though, to meet the first, we may assume that the winter decim- 

 ates their numbers, or that the spring weather is not favorable to their 

 increase ; and to meet the last we may conjure up a hundred reasons 

 yet assuming is not knowing, and we must content ourselves with the 

 facts as they occur. 



In conclusion, it will afford a grain of comfort to those who have 

 had wheat fields cleaned off by this worm, to know that their wheat 

 is not necessarily ruined ; for, as I personally ascertained, wheat that 

 had been thus cutoff in the fall of ISO'S made a good stand the follow- 

 ing spring; and in one instance, where part of a field had been in- 

 vaded and the rest left untouched, it really appeared that the part 

 which had been eaten off yielded the heaviest. Mr. Huron Burt, of 

 Callaway county, Mo., also informs me that this insect always leaves 

 blue-grass untouched. 



Prodenia autumxalis, Riley. — Imago (Fig. 46, a, b and c.) — Front wings narrow with the 

 apex usually well rounded, and with the middle of the hind margin sometimes, hut not often, ex- 

 tending beyond apex : general color mouse-gray variegate 1 with smoky-brown, fulvous and pearly 

 or bluish-white ; apical patch bluish-white and never extending beyond nerve 5 : the subterminal 

 line — which is pale and bends like a bow, approaching nearest the terminal line between nerves 3 

 and -1 — generally blends with this patch so as to appear to start from its lower edge, but is some- 

 times well separated from it so as to be traced further towards apex: dark space preceding- subter- 

 minal line, confined between nerves 3 and 5, blending gradually with the rest of the wing, barely 

 showing two darker sagittate spots : transverse anterior and transverse posterior either subobsolete 

 or tolerably well defined, each by a geminate dark line : basal area divided longitudinally by an 

 irregular dark line, the wing below it quite light-colored: orbicular spot large and elongated, a 

 little lighter than surrounding surface, and well defined by a fulvous annulation, thff pale oblique 

 shade which generally encloses it in this genus confined to a fulvous shade above, and either a more 

 distinct fulvous line behind or none at all : reniform spot generally dark, but sometimes lighter 

 than space preceding ; not well defined, the small pale spot at top being generally distinct, and 

 either partaking of the same form, or resembling- the small letter c [left wing]; the Ipwer edge oc- 

 cupied by a distinct white dash, which however never extends beyond it and but seldom shows any 

 tendency to furcate with the nerves : four tolerably distinct equidistant pale costal spots from 

 reniform spot to apical patch : terminal line pale, even, parallel with posterior margin : terminal 

 space dark, except near apex and anal angle, divided into subquadrate spots by the pale nerves: 

 fringe either broad or narrow, of same color as wing, with a narrow darker inner line, relieved by 

 two very fine paler ones which are barely distinguishable : under surface smoky, but paler inte- 



■ Many of the Fall Army-worms had the thoracic joints of the body more or less covered with 

 the egg- of a Tachina fly, and 1 have hred from the worms the same parasite (Exorinta leucanice, 

 Kirk; 2d Rep. Fig. 17) which infests the true Army-worm, and still another allied species (Tachina 

 archippivora) which infests the larvae of the Archippus butterfly, and will be referred to on a fu- 

 ture page. 



