435 



or at most merclv distortiiiii; or ciirliiii:: iho loaves. I'hcro are 

 a few species, however, which have tlie hahit of caiisiii<>' char- 

 acteristic galls to grow on leaves and inhahiting thc^ inside of 

 these galls. 



These species are fonnd in a good many i-cgious of 

 I the sonthern hemisphere and of the southern ])art of the 

 I northern hemisphere. The most northerly representative of 

 this type of Trioza is the species arbolensis fonnd in southern 

 United States. One species occurs in Mexico, nuiking galls on 

 avocado leaves, two have been recorded from South America 

 and several from sonthern Asia, a large nnnil)er from Ans- 

 tralia, a few^ from ]\ralay Archipelago and still others from 

 other southern countries. A few of these have been assigned 

 to another genns, Cecidotrloza, and it is possible that when 

 our knowledge is more complete all these gall makers will be 

 referred to such a genns. 



Xearly all of these gall-forming species of Trioza resemble 

 each other in certain wing venational characteristics and in the 

 male genitalia, thns indicating perhaps a generic relationship 

 to each other and distinct from other species of Trioza. The 

 lirst marginal cell of the forewing is of a pecnliar shape, the 

 cnbitns forking at about the midpoint or basad of it. The male 

 anal valve in lateral, or profile, view has a straight anterior 

 margin bnt the posterior margins (the lateral wings) are char- 

 acteristically convex. 



Although the Hawaiian species have undergone changes in 

 the shape and form of the head, armature of the legs and size 

 and shape of the wings, yet a marked homogeneity in the char- 

 acters al)ove referred to shows not only a close inter-relation- 

 ship among these species but also points to a close affinity of 

 these with the gall forming species of Trioza in Malay Archi- 

 pelago and elsewhere. The fact that many of the Hawaiian 

 j species are gall forming is further indication of tliis atlinity. 



Most of the Hawaiian species live upon the foliage of 

 Metrosideros polymorpha Gaud., called by the Hawaiians 

 ''Ohia lehua", and other species of the same genus. One (and 



