AMERICAN PSYLLIDJE III (Triozin^) 



BY D. L. CRAWFORD 



The following descriptions complete the study of the Triociiiac as based 

 on the material now at hand. The synopses which accompany the descriptions 

 will supersede and replace the provisional synopsis as iiuhlished in an earlier 

 number of the Journal. Although there are several new genera and many 

 new species here presented, yet there must be many more new forms in 

 America still, and until these are studied thoroughly nothing in the nature 

 of a monograph can be attempted. In the interest of science, therefore, it is 

 hoped that all the material possible will be made available for study, for the 

 furtherance of the knowledge of this important group of insects. 



The facial cones furnish striking and constant generic characters, as do also 

 the pronotum and mesothorax. Undue emphasis, however, was at first put on 

 the position and trend of the facial cones ; this is of secondary importance, to 

 be sure, but not a primary diagnostic character, since it separates synoptically 

 the sexes of a species, as occurred in T. tripunctata (Fitch) Riley. A striking 

 variation occurs in the form of the pronotum. In the genus Allotrioza the 

 pronotum is relatively very long and extending on its dorsal surface from the 

 anterior margin of the dorsulum to the posterior margin of the vertex. In all 

 or most of the other Triodnae the pronotum is relatively shorter and is 

 partially concealed by descending behind the posterior margin of the vertex, 

 and does not attain posteriorly to the surface of the dorsulum ; this has been 

 spoken of as the pronotum depressed below the dorsulum and head. The 

 dorsulum in the latter case is usually roundly pointed cephalad, and of rather 

 a spherical-triangular shape. 



Very good diagnostic characters lie in the genitalia of the male, but since 

 often only the female is represented in the collections, these characters can 

 not well be used. In the preliminary study the term anal projection was 

 suggested for the dorsal portion of the male genitalia. The term anal valve 

 is more suitable and will be used hereafter. The lateral view of the anal 

 valve is very important and should always be represented by a good clear 

 figure. Of the female genitalia three general types are easily recognizable : 

 the short, the long, and the extremely long and slender. The first is, typical 

 in the species Trioza salicis, the second in T. quadvipitnctata. and the third in 

 T. longistylns. 



The veins of the forewings are nearly always set with fine microscopic hairs 

 at regular intervals, but with very few exceptions these setse are visible only 

 under very high power; occasionally, however, as in T. mcxicana, they are 

 more conspicuous and easily visible under a low power of magnification. 

 In many forms the wing membrane is covered with punctural dots but these 

 are not visible except under the high power ; in a few species these are very 

 conspicuous, giving a fulvous, smoky appearance to the wing. 



