191 



ANATOMIGAL NOTES ON A MEMBRAGID 



by J.-G.-C liersliaw. 



This Membracid, Tricentrus alboniaculatus Dist., lias within 

 récent years (about 1902) arrived in Ihe Hawaiian islands, where it 

 feeds on Eucalyptus trees — also a comparatively récent introduc- 

 tion — and can now be found in fairly large numbers in certain 

 localities on the island of Oahu. The nymphs feed chiefly on the 

 tender succulent llower-buds, and are attended by swarms of a 

 small reddish ant, Pheidole megacephala. The ants tittilate the anal 

 segment of the nymphs with their antennœ and fore tarsi, and the 

 nymphs then protrude the anal segment and anus and exude a glo- 

 bule of clear liquid, evidently the excrément, vvhich the ants 

 eagerly drink up. The nymphs can elevate the ninth segment of 

 the abdomen practically to a right-angle with the rest of the body. 

 Guriously enough the nymphs, unlike the generality of leaf-hop- 

 pers, hâve no jumping power whatever, but merely try to escape 

 by walking even when touched and annoyed. AU, or nearly ail, the 

 tegumentary bristles of the nymph are hollow and communicate 



an 



Fig. 1. 



with the body cavity. The row of dorsal abdominal bristles in the 

 newly-hatched nymph differs from that of subséquent instars. In 

 the former the bristles are large and curved like a sickle, in the 

 latterthey are depressed almost horizontally and are comparatively 

 smaller (Fig. 1). 



The adult female lays its eggs singly in the soft tissue of new 

 shoots and flower-buds of Eucalyptus, and usually makesaslit into 

 the middle of the stem, occasionally piercing right through to the 

 other side. The egg is inserted with a rather large amount of col- 

 leterial tluid. 



