SCIENCE. 



467 



A REMARKABLE INVASION OF NORTHERN 

 NEW YORK, BY A PYRALID INSECT :* 



Crambus vulgivagellus. 

 (Abstract.) 



BY J. A. LlNTNER. 



About the middle of May, of the present year (1881), 

 a serious invasion of St. Lawrence county, N. Y., and 

 several of the adjoining counties, by the " Army Worm," 

 was announced by the newspapers, and by letters ad- 

 dressed to me. It was stated that many pastures had 

 been completely ruined, and the entire destruction of the 

 pastures and meadows was feared. I had never witnessed 

 the operation of the Army Worm — comparatively rare in 

 the State of New York — and I at once visited the infested 

 locality for personal observations. 



The reports had not been exaggerated. The ravages 

 were widespread and serious, already extending over 

 eight of the northern counties. Hundreds of acres of 

 grass presented a brown appearance, as if the grass had 

 been winter-killed. A pasture lot of fifty acres, exam- 

 ined by me, which ten days before offered good pastur- 

 age, was now entirely brown from the complete destruc- 

 tion of the grass — so thorough, that in places not a blade 

 could be discerned in an area of a square yard, by care- 

 ful search. Numerous dead caterpillars were adhering 

 to the dried stems of last year's grass, which, it is be- 

 lieved, had fallen victims to starvation. 



Several interesting features characterized this attack. 

 It appeared first on upland pastures, differing in this 

 respect from the invasions of the Army Worm, Leucania 

 unipuncta. 



The progress was remarkably rapid. A browned 

 patch would rapidly extend its area, until it overspread 

 the entire field in ten or twelve days. It could not be 

 ascertained if this was by the spread of the larva? from 

 certain points, or from the unequal hatching of the eggs, 

 uniformly distributed over the field, as influenced by va- 

 rious conditions. The secresy of the depredation was 

 unusual. The larvae had seldom been seen and never ob- 

 served in active feeding. It was believed that they fed 

 at night, by drawing in the blades of grass to their sub- 

 terranean retreats. 



In two instances the larva? were observed in immense 

 numbers, collected on trunks of trees — so numerous that 

 they could have been scooped up by handsfull. One of 

 the reported localities was visited by me where the as- 

 semblage had been noticed three days before. The tree- 

 trunk, at its base, was found to be enveloped by a web of 

 silk, as was also an adjoining stump, of so firm a consist- 

 ence that it could be lifted up in a sheet, like a piece of 

 woven silk. The cause of the congregation at this point 

 could only be conjectured, but it was thought it might 

 have been for shade, after the complete destruction of 

 the surrounding pastures. It was not for feeding on the 

 foliage, for the grasses were alone eaten by the larvae. 



It was generally accepted throughout the entire region 

 as an army-worm invasion, and the most disastrous con- 

 sequences apprehended. The papers abounded with no- 

 tices of it. Farmers commenced to dispose of their 

 cattle, in the prospect of their ruined pastures and mead- 

 ows. It became the one topic of village conversation, 

 and general alarm prevailed. 



The caterpillars observed and collected by me in Mor- 

 ley and Potsdam, by digging in the soil, and occasionally 

 finding one on the surface, were slender, cylindrical, six- 

 teen-footed, of a sordid or obscure greenish color, with a 

 shiny black head. They were destitute of lines or other 

 ornamentation than some verrucose spots on the dorsal 

 portion. The average length was three-fourths of an 

 inch. 



I was unable to identify these with Luecania uni- 

 puncta, for they were quite unlike the mature form of that 



*Read before the A. A. A. S., Cincinnati, 1S81. 



species which I had alone seen. Yet it was possible that 

 they had additional moltingsto undergo, which might re- 

 sult in a material change of appearance. Their habits 

 seemed to be quite different from those of the army- 

 worm, and it was nearly two months too early for an in- 

 vasion of that species. 



Of the larvae which I had brought from Potsdam for 

 rearing and ascertaining the species, nearly all died 

 shortly thereafter. Only a single one developed, giving me 

 a small Pyralid moth — Crambus cxsiccatus. Additional 

 ones were sent me, at my request, from Potsdam. They 

 were quite different from those previously collected and 

 observed by me, but it was believed by my correspond- 

 ent, as the result of observations made, that the molting 

 through which they had just passed had produced this 

 change. 



I suspected that two species were associated in the at- 

 tack, but other pressing duties at the time prevented a 

 decision upon this subject. Some of the examples re- 

 ceived were submitted to Prof. Riley, who was able to 

 identify them as the larvae of a rather rare Noctuid — 

 Nephelodes violans, which he had known in Missouri. 

 The occurrence of the species in such numbers— more 

 than a dozen in lifting a small piece of a rail — was an in- 

 teresting discovery. In some communications contrib- 

 uted by me to some of the newspapers of Albany and 

 Northern New York, I ascribed the above ravages to 

 Nephelodes violans. Farther study led me to believe that 

 I had been hasty in my reference. 



Early in July, Mr. J. O. Adams, of Watertown, N. Y., 

 where the ravages of the same insect had also been ob- 

 served, furnished me with information and material that 

 convinced me that N. violans was only chargeable with 

 a small portion of the above injuries, and that the prin- 

 cipal depredator was the smaller larva observed and col- 

 lected by me, which, from the cocoons forwarded to me 

 at this time, undoubtedly belonged to the Pyralidae. The 

 cocoons were taken from the infested fields at Watertown, 

 from just below the surface of the ground, where they 

 were so numerous that a half dozen could be taken Irom 

 a sod the size of a man's hand. On opening the cocoons, 

 the larvae were found lying within them, still unchanged, 

 although they had been made over a month before, and 

 they were identical with my Potsdam collections. Ad- 

 ditional cocoons were opened by me early in July, when 

 the larvae were still in their untransformed state, in which 

 they had at this time been remaining for from a month 

 to a month and a half. 



The delayed pupation is an interesting item in their 

 history. It is known to occur in some of the Bombycidae, 

 among the Notodontas for example, when it extends over 

 the winter, and the pupa state is assumed in the spring, 

 a short time before the emergence of the perfect insect ; 

 but it was new to me at this season of the year. 



Dr. Hagen, to whom I communicated the fact, was 

 unable to find any record in the extensive library at Cam- 

 bridge of such delayed pupation among the Pyralidae, 

 although Prof. Riley informs me that he had known of 

 its occurrence in some of the species. 



On the 6th of August, the first moth from the Water- 

 town cocoons was disclosed, and it proved to be Crambus 

 vulgivagellus. The interesting question as to which of 

 our insect depredators was chargeable the ravages in 

 Northern New York — more injurious in the extent of 

 territory embraced than in an army worm invasion — -was 

 decided. The new enemy, the latest addition to our list 

 of formidable insect pests, was found to be a modest, in- 

 conspicuous, hitherto unobtrusive little Crambus. It had 

 long been known in our cabinets, but had never before 

 presented itself as an injurious insect. 



It is probable that several accounts of injuries to pas- 

 ture lands, in New England States, during the last three 

 or four years, which have been ascribed, either to the 

 army-worm or an unknown depredator, are due to this 



