110 THE CAUSES WHICH PROPAGATE 



keepers, from the sharp prick it administers with its rostrum. 

 Doug-las and Scott say of it : " Found occasionally in houses 

 and fowl-houses, it also tiies by night to lights in windows. 

 The larva feeds on the Bed Bug, and other insects, and covers 

 itself with dust.^' The problem as to how this insect produces 

 a monotonous stridulation has been thus solved by Herr 

 Westring. " I took a Reduvius joersonatiis, Wolff, and remarked 

 after this had been stuck on a j^in it nodded with its head, 

 and at such times the stridulation was heard. As I observed 

 the neck was shining or smooth, I could not bring myself to 

 consider that part an organ of sound. On pushing a fine brush 

 between the sucker or rostrum and the canal, the sound ceased, 

 although the movement of the head was continued, but on its 

 removal the sound was again heard. This experiment was 

 repeated with the same result. So I considered it settled that 

 the stridulation was caused by the friction of the rostrum in the 

 canal on the prosternum. This I established, on observing with 

 a microscope that the canal in a certain light was covered with 

 the finest transversal edges, starting from either side and 

 running obliquely backwards, meeting in the middle at an 

 obtuse angle. The active organ was the needle-fine point of 

 the rostrum, which moves over the canal at an inclination of 

 about 45'^.''^ Ray compares the cry of this bug to the chirping 

 of a grasshopper. 



Various species of Reduviidae I lately procured performed in 

 similar fashion. Placing the indurated or tempered termination of 

 their short and thick rostium in the lenticular striated groove 

 extending from the front edge of the prosternum to the insertion 

 of the first pair of legs, they then commenced to rub this ungular 

 point backwards and forwards by a nodding motion of head from 

 its prothoracic articulation, the length and celerity of the move- 

 ment perceptibly regulating the fulness and pitch of the notes, 

 while the organic structures and frictional surfaces determined 

 the gamut. 



The first stridulator I met with, the pupal form of 

 Reduvius ^^ersonatns, was taken begrimed with particles of 

 dust, within the folds of a sun-bleached muslin window-blind ; 

 the second, OncocepJialiis notafus, Eamb., was captured in a 

 railway carriage near Foggia, both in the month of May. 



