16 



INSECTS OF SAMOA. 



same genus are very attractive to Euploea mathewi in Tonga, and to several 

 species of Euploea in the New Hebrides (Buxton) and the Solomons (Woodford, 

 1890, p. 94). In all these cases it is noticeable that only males are attracted, 

 though both sexes frequent flowers, and that it is not the flowers but the dead 

 and withering twigs and branches that are attractive. I once saw many 

 hundreds of Euploea sclimeltzi on the fruit- clusters of T. argentea in Savai'i, but 

 even in this case it was the dead and withered clusters that were preferred. 

 The tree does not seem to be attractive to any other butterflies, except 

 moderately so to males of D. m. melittula, and it is difficult to imagine in what 

 the attraction lies ; no exudation of any sort was observed. Since the 

 attraction is almost confined to males of the genus Euploea, it seems not 

 impossible that the scent may resemble that of a virgin female, and that the 

 volume of it is sufficiently great to make up for slight differences, and hence 

 make it attractive, not to one species of Euploea only, but to many. It should 

 be noted that this habit is quite distinct from that of roosting in flocks, which 

 is so common in the genera Euploea and Danaida. In Tonga, in addition to 

 seeing the males of E. mathewi on Tournefortia, I was able to find both sexes 

 going to roost in the evening about half a mile inland ; they did not appear to 

 show a preference for any particular tree, and there were no specimens of 

 Tournefortia in the neighbourhood, this tree being entirely confined to the 

 beach. The case seems to some extent parallel with the attraction of isoeugenol 

 and methyleugenol for certain Trypetidae, and of naphtha and kerosene for 

 Ceratitis captitata ; this also has not yet found a satisfactory explanation, but 

 has been attributed to some form of sex-stimulus, since in this instance also it 

 is the males only that are attracted. 



Variation is considerable in both sexes, both in size and markings, but 

 all forms may be taken together at the same time and place. The white markings 

 on the upperside are usually much better developed in the female than in the 

 male ; the reduction of pattern, especially in the latter sex, may go so far as to 

 leave no indication of the white markings except the short row of sub-apical 

 spots, while on the other hand all the markings may be well developed. In 

 some specimens the forewing pattern is well developed, and that of the hindwing 

 almost obsolete. My largest specimen is 69 mm. in expanse, and my smallest 

 60 mm. ; both are males. 



On the 7th April, 1924, Buxton observed a very interesting flight of this 

 species in the district of Aleipata, Upolu Island. At about 9 a.m. he found the 



