102 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxvi. 



fringed, and not folded; they have few veins, and upon the hind edg-e 

 of the base of each there is a usuallj'" distinct lobe or scale. The fore 

 and hind wings are formed quite similarly. When at rest, the wings 

 are folded back flat upon the abdomen, the fore wing covering the 

 hind one completely and the pairs lying parallel in the Terebrantia, 

 while in the Tubulifera the wings all overlap at their tips so that the 

 full surface of only one can be seen when the}^ are at rest. The wings 

 are usually about as long as, though sometimes much longer than, the 

 abdomen, but in many Tubulifera they are shorter. The wings of 

 ^olothripidffi are proportionally the broadest in the order, being in 

 the middle about one-seventh as broad as their length. Those of 

 Thripidte are much more slender, ranging from one-tenth in the fore 

 wing of Parthenotlirifs to about one -twenty-sixth in that of some 

 SerlcotJirips; the average in the species of this famih^ known to me is 

 about one-fifteenth. Three general types of wing are found in the 

 order, each of which is characteristic of a family. 



Family types. — ^^olothripidfe possess wings which are compara- 

 tiveh^ broad, as we have seen. Their breadth continues nearly to their 

 tips, where they are broadly rounded. (Plate I, fig. 2.) The hind 

 wings resemble the fore wings closely in general outline and size. 



The wings of Thripidre are distinctly different from the preceding. 

 Besides being much more slender, they taper from base to tip, where 

 they are sharply pointed, the whole wing being usually slightly curved 

 so as to be quite sabre-shaped. (Plate II, figs. 16, 23.) The fore wing 

 of Parthenothrips approaches most closelj'^ that of ^olothrips, being 

 broad and straight but pointed instead of rounded at the tip, and the 

 Venation is very different. The hind wings are somewhat shorter and 

 narrower than the fore wings. 



The third type of wing (Plate VII, fig. 75), found in the PhlcBothrip- 

 idsB, resembles that of >^Eolothrips in being broad and rounded at the 

 end. The hind wing is also similar in size and form to the fore wing. 

 In some species the wing is narrowed in the middle so that it reseml)les 

 somewhat a shoe sole. Other characters, as venation, fringing, etc., 

 separate them very decidedly from the ^Eolothripida?. 



Venation.— The venation is even more characteristic of the families 

 than the form of the wings. In the ^^olothripida?, the fore wings 

 show the most complex venation found in the order. They are entirely 

 bounded ])y a strong ring vein and pierced b}^ two longitudinal veins 

 extending from the base to near the tip, where they bend outward and 

 join the ring vein. Four or five cross veins are also present, two 

 uniting each long vein with the ring vein at about the first and second 

 thirds of the wing and one cross vein uniting the long veins before 

 the middle. The hind wings have no fully developed veins. 



In the Thripidaj the veins are much less prominent, except in Par- 

 thenothri^ys. One or two longitudinal veins are present, but cross 

 veins have very nearl}^ disappeared, though vestiges of most of those 



