﻿52 



NINTH ANNUAL REPORT 



vicinity of Philadelphia. The insect is also alluded to in the Country 

 Gentleman for July 15, as doing injury in York Co., Penn. 



Now the interesting feature about this insect is that its appear- 

 ance in such destructive numbers and its habit of attacking wheat 

 heads are modern phenomena. None of the early writers on economic 

 entomology in this country refer to anything of the kind, and the first 

 notice that I recollect seeing of this habit in this insect was in the 

 Summer of 1872, when, in the N. Y. Trihune, Mr. R. W. Hudson of Hunt- 

 ington county, Penn., described a worm which seriously injured his 

 and a neighbor's oats fields by destroying the heads, and which was 

 erroneously supposed to be the Army Worm. It is highly improbable 

 that the conspicuous ravages of a worm of this kind could have gone 

 unnoticed and unrecorded, either by farmers or entomologists, if they 

 had occurred ; and the fact that the species shows a large degree of 

 variation, warrants the belief that it has been lately modified. Feed- 

 ing originally on some wild grass ; undergoing modification, and first 

 acquiring the peculiar habit here described in York county, Pennsyl- 

 vania, this wheat-head-feeding race may subsequently have been car- 

 ried to Kansas either in the chrysalis or moth state, or, what is more 

 likely, in the e^g state on grain and grass. This would account for 

 its attracting attention there before it was noticed in the intermediate 

 country. Yet a dark form occurs in the intermediate country, because 

 I reared such a dark form, answering to Hiibner's figure, in 1870, from 

 larvge that had transformed in a rye field at Kirkwood, Missouri. The 

 wheat feeding race may be expected to widen the area of its devasta- 

 tion until it spreads over the larger part of 

 the country, and, like its long and well known 

 congener, the true Army Worm, becomes un- 

 usually abundant and injurious, whenever the 

 conditions are favorable to its multiplication' 

 We may also expect an increasing tendency 

 in the species to vary, 'and give rise to still 

 other varieties and races that will perplex definers and describers. 



HABITS AND NATURAL HLSTOKY. 



As I have abundantly proved, by rearing one generation from the 

 other, this insect is double-brooded with us.* The first moths appear 



Moth of Wheat-head Ahmy 



Wo KM. 



« It Is quite probable, however, that, as Avith the true Army Worm— rwhich. as we have .iusl seen, 

 is floub'.e-brooded lurlher iioi-th— this, its congener, produces but one brood annually in the higher 

 latitndi-s, the insects liiliei-nating mostly in the perfect state Indeed, there would seem to be such 

 irrcfiuhuity m this rcjiard that both iieculiarities may occur in the same locality ; for of a number of 

 chrvsalides colUclcil at Lionville, Pa., in August, by Mr. Smedley, from among the sh.itterings that 

 leU'lrom the mow when threshing wheat that had been harvested early in .luly, a few only gave out 

 the moths, and the rest are hibernating. Moreover, it would seem that where one brood only is pro- 

 duced, the moths i)artakeof the intermediate characters between the suMinii'r lirond, which has the ijale 

 secondaries and accords so hilly with Guenee's description, and the spring brood with ■ arker secon- 

 daries, which accords with Grote's Hoivciji; for specimens l)red by Mr. f.intner, of Albany, New 

 York, in August, have, in l)oth sexes, the intermediate size and the secondaries quite distinctly dusky 

 around the exterior border but not basalt y. 



