INTRODUCTION cxcvii 



notably different from those of the other Reduvioli, whether of the fully-winged group 

 or of the flightless Nesotyphlias. It is quite possible that new species will be dis- 

 covered connecting the well-winged forms of Reduviolus more closely with the flight- 

 less Nesotyphlias, and such a discovery would be of considerable interest. 



As in so many other Hawaiian genera containing many species, Reduviolus 

 presents a series of forms mostly very closely allied and sometimes more or less difficult 

 to discriminate ; some, indeed, without minute and careful study in the field it will 

 be impossible to fix as being certainly good species or only variations. Amongst these 

 occur a few forms, notably distinct and separable at a glance, though manifestly allied 

 to the others. Many of the species exhibit considerable variability not only in colour, 

 but in such characters as the shape of the pronotum, the thickness of the basal joint of 

 the antennae, etc. Such variations occur in individuals of a species taken in company. 

 It is noteworthy that whereas R. blackburni varies in the condition of tegmina and 

 wings, being apparently affected by temperature or humidity or both combined, other 

 species, such as R. oscillans, which are found under conditions, as diverse, seem to be 

 nowise affected by these conditions. 



The variety of R. kei-aspkoros with flavescent tegmina on the basal part is 

 interesting, as nearly reproducing" the colour pattern, that is, so far as we know, fixed as 

 a specific character in R. sharpianus. 



On Oahu I have made some attempt to study the habits of two forms of the 

 flightless Nesotyphlias, which are very similar, with a view to deciding on their distinct- 

 ness as species. On the whole their habits seemed to confirm their distinctness, seeing 

 that though both might be found under apparently the same conditions, the one would 

 also thrive in situations never occupied by the other. Thus though to some extent 

 alike in habits, in others they differed, and this partial difference in habits was always 

 accompanied by a definite difference in structure. 



The habits of the Hawaiian Reduvioli are of considerable interest, for whereas 

 some apparently have their habitat solely on one kind of tree or plant, others are less 

 particular in this regard. It is noteworthy that the species, that are attached to a 

 single kind of plant, are invariably of very distinctive superficial appearance. In 

 determining the true habitat of a Reduviolus attention should be paid only to the trees 

 or plants affected by the nymphs, because in the fully-winged forms, which fly 

 sufficiently well, though weakly, individuals occur casually on plants, with which they 

 have no real connection. R. kahavalu attached to Sophora chrysophylla, R. tarai on 

 Cyathodes, and R. truculentus on Pipturus are good examples of the restricted habitat. 

 The Reduvioli being carnivorous, it might be supposed that the restricted habitat of 

 the species just mentioned (and of others to which I have not paid special attention in 

 the field, in order to observe them in situ on their favourite plant) was due to the fact 

 that these special plants furnished a special prey. This I believe not to be the case, 

 but the association is rather for concealment, since either in the nymph or adult or in 



