154 SIXTH ANNUAL REPORT 



wing-covers; a few stridulate during flight by rubbing together the 

 under surface of the front and upper surface of the hind wings. The 

 Crickets ( Gryllidce) stridulate by rubbing together the strong middle 

 veins at the base of their wing-covers ; while the Katydids stridulate 

 by friction of the large veins situated mostly on the inner margin of 

 a talc-like plate at the base of the wing-covers.f 



We have in this country four Katydids that are tolerably com- 

 mon. They all dwell among trees and shrubs, and might far more ap- 

 propriately be called tree-vaulters than grass-hoppers. They are all 

 of a green color, with very long, slender legs and antennae, and the 

 females are all furnished with curved or saber-shaped ovipositors, 

 formed of two pairs of flattened sheaths which inclose two narrower 

 pieces. The base of the front tibias or shanks is somewhat dilated, 

 with an oval cavity each side, closed by a membranaceous cover- 

 ing. In the Oblong-winged species, the first and middle shanks have 

 such cavities, but in the other three species, it is found only on the 

 front shanks. 



Before passing to the consideration of our individual Katydids, I 

 wish to call especial attention to the fact that, so far as is recorded, 

 their representatives belonging to the same family in Europe all 

 oviposit in the ground. As a rule, in animal and plant life, a special 

 organ subserves some special purpose. The front limbs in the Bat, 

 by a great elongation of the finger-bones, subserve the purpose of 

 wings: in the Whale they are shortened so as to answer the purpose 

 of fins ; and in the Mole they are wonderfully modified for digging, 

 very much in the same manner as we see them modified in such bur- 

 rowing insects as the Tumble-dungs and Mole-crickets. Sometimes — 

 as in the singular case mentioned by Darwin, who found, on the tree- 

 less plains of South America, a species of wood-pecker which still 

 retains the climbing feet of the true wood-peckers, although there 

 are no trees for it to climb — a species deviates from the habits of its 

 family, and no longer has occasion to use a certain organ, which, nev- 

 ertheless, it retains in a rudimentary condition. 



Misled by Harris, who, in the earlier edition of his work, stated 

 that all our grasshoppers laid their eggs in the ground, and in the 

 last edition, expressly states (p. 156) that some of them — e. g.^ the 

 meadow-grasshoppers — do so ; and conceiving, also, from the state- 

 ments of Harris, that all our Katydids fastened their eggs externally 

 to twigs, Mr. Walsh considered Wxe ovipositors of these Katydids 

 rudimentary, and the habit exceptional. He wrote, under date of 

 February 17, 1863, in the Prairie Farmer: "Why, while many 

 other families of insects, which deposit their eggs on the surface of 

 twigs, have no ovipositor, the common Katydid and several allied 



