Vol. XXV] ENTOMOLOGICAL NEWS 465 



among the Xiphidions is a close approach to that of the cone- 

 headed grasshoppers Conocephalus triops and C. robiistns. 



From the preceding remarks concerning the musical habits 

 of the Xiphidions, it is evident that the stridulations of these 

 little locusts are similar to the stridulations of the Orcheli- 

 mums on the one hand and to those of the cone-headed grass- 

 hoppers Conocephalus on the other. 



Stridulation unquestionably plays a very important role in 

 the mating activities of the musical Orthoptera. It is a part 

 of the active courtship behavior of the males. In the imme- 

 diate presence of the females, the males, under the influence 

 of strong sexual excitement, sometimes become very energetic 

 in their stridulatory activities. At such times, however, the 

 notes are often interrupted and irregular, and may not repre- 

 sent the characteristic mode of stridulation of the species. 

 From a study of various katydids in confinement, it is evident 

 that something akin to a keen sense of rivalry exists between 

 the males of a species. 



A single male katydid or locust of almost any species when 

 confined in a room will stridulate very vigorously in response 

 to other males out-of-doors, and sooner or later will make its 

 way to the screened window in an attempt to escape and seek 

 its noisy rivals. Among the musical Orthoptera this sense of 

 rivalry in a great measure appears to be one of the strongest 

 impulses leading to the act of stridulation. The writer has 

 spent much time among colonies of different species of musical 

 locusts and katydids, closely observing the various movements 

 of the individuals. Tn general, the females are not prone to 

 move about as actively as the males. The males, however, as 

 soon as the time for stridulation has arrived, become alert, 

 restless and climb or fly more or less actively from point to 

 point, stridulating more or less persistently in the meantime. 

 Observation has shown that many of these movements have 

 been made in order to approach rival males in the vicinity. 

 The writer has repeatedly noted these movements in colonies 

 of Microcentrum rhombifolium, Amblycoryphd oblongifalia, 



