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ON THE GENUS DIATRiEA. 



By Prof. C. H. Fernald. 



Amherst, Mass. 



The genus Diatrcea was established by Guilding in 1832, for the 

 species which he described as Diatrosa sacchari, but which is without 

 doubt the same species that Fabricius described in 1794, in his Entomo- 

 logia Systematica, Vol. Ill, Part 2, p. 238, under the name PhalcFiia 

 ■saccharalis. The habits and life-history of this species have been given 

 in an excellent manner in the Report of the Department of Agriculture of 

 the United States for the year 1880. 



This genus may be characterized as follows : 



Eyes large, hemispherical and naked. Ocelli wanting. Labial palpi 

 horizontal, nearly as long as the head and thorax. IVIaxillary palpi tri- 

 angular and about as long as the head. Antennae about two-thirds as long 

 as the costa. Front slightly swollen but varying in the different species. 



Fore wings about twice as long as wide, the apex right angled and 

 the outer border slightly and regularly rounded. There are twelve veins, 

 of which vein i is simple at the base and ends a little before the anal 

 angle ; vein 2 arises a little beyond the middle of the median vein and ends 

 in the anal angle ; vein 3 arises halfway between the origin of vein 2 and 

 the end of the median vein ; vein 4 arises at the end of the median where 

 the cross vein begins ; vein 5 arises very near it from the cross vein. 

 From this point to the origin of vein 6, the cross vein is very fine and 

 turns in towards the base of the wing forming a right angle. Vein 6 

 arises quite near to the origin of 7 which last arises from the end of the 

 subcostal and ends below the apex. Veins 8 and 9 are from the subcostal 

 a little before the end. Vein 8 ends in the costa quite near the apex and 

 9 ends in the costa a little before it. Vein 10 runs near to and parallel 

 with the stem of 8 and 9, through the first half of its length. Veins 1 1 

 and 12 unite nearly above the origin of vein 10, and separate again before 

 reaching the costa. 



The hind wings have eight veins, three inner border veins and the 

 frenulum is single in the male but divided in the female. The origin of 

 veins 2, 3 and 4 is equally distant, but vein 5 arises from a short stem 

 with 4. Vein 6 arises near the base of the stem of 7 and 8. The cross 

 vein forms an acute angle pointing towards the base of the wing. The 

 basal part of the median vein is pectinated on the upper side. 



The legs are moderately stout and the vestiture is smooth over the 

 whole surface of the body and wings. Genital hook present in the male. 



The described North American species may be separated by the fol- 

 lowing table : 



