90 BULLETIN 85, UNITED STATES NATIONAL MUSEUM. 



(Koebele), September, on Salix lasiolepis; Ormsby County, Nevada 

 (C. F. Baker); Colorado (no data), on Salix; Santa Fe, New Mexico 

 (H. S. Barber); American Forks, Utah (Hubbard and Schwarz); 

 Oregon (Koebele); Easton, Washington (Koebele); Algonquin, Illi- 

 nois, July 12, 1895. 



Nymphs, also, have been taken on Salix lasiolepis, showing that 

 the willows are undoubtedly the food plant of the species. 



This is a very abundant species and subject to some variation, as 

 the above synonymical list shows. After careful examination of 

 Numerous specimens from many localities and comparison with Sulc's 

 excellent figures ('11: pi. 14), it is apparent that all these variants 

 (formerly described as species) belong to one and the same species, 

 and, furthermore, that this species is identical with the European 

 species maura Forster. The distribution seems to be exceedingly 

 wide. TJie food plants, both here and in Europe are species of Salix, 

 the willows. 



According to the description by Sulc (I have seen no European 

 specimens) there are some slight differences between the European 

 and American forms. The head, in the latter, is typically orange 

 with some black, while Sulc described it in the European forms as 

 typically mostly black. The abdomen, too, in the American forms 

 is typically white or pale ventrad, while Sulc describes the abdomen 

 as entirely brown. In the American forms, however, these characters 

 are not constant, and therefore, these differences in description 

 between the American and European forms are not surprising. 



The following is taken from Loew ('84: 144-145) : Nymph flat, 2.5 

 mm long and 2 mm broad, egg-shaped, glabrous, green, yellow, or 

 yellow with greenish spots; with a dark brown dorsal stripe and 

 several cross bands; eyes red; with a fringe of hyaUne hair-like pro- 

 jections around entire margin, about as long as width of brown 

 bands. 



Found singly on the under surface of leaves of Salix alba and -S'. 

 purpurea; Adults emerge about the first of October and over-winter. 

 In the following May and June the females oviposit. Parasitized 

 nymphs are black and always on the upper surface of the leaves. 



It is quite probable that the American forms pass through a similar 

 life history, since adults may be collected in late autumn. 



The following two species, T, salicis and T. varians, are very 

 closely related to this species and often very difficult to distinguish 

 from it. The male genitaUa are very similar in the three species, 

 differing only in slight details; the female genital segment, however, 

 shows some specific differences. It is possible that these three 

 should be considered as one polymorphic species, but since they can 

 be distinguished it is just as well to regard them as specifically 

 distinct. T. marginata is, also, closely related to this group of three 

 species. 



