Ixxx FAUNA HAWAIIENSIS 



Hibiscus brackenridgei, composites such as Lipochaeta and depauperated forms of 

 Santahwi. These lowland bees have taken freely to many introduced plants, such 

 as Pj'osopis and other acacias amongst trees, as well as garden flowers of various 

 kinds. In the mountains the Ohia tree in general is visited by all species of the 

 genus, as it affords abundance of nectar easily reached by these short-tongued bees. 

 Many other flowers are attractive in their season, Acacia koa, Stranssia, the mountain 

 species of Scaevola, Rubus viacraei, etc. In the regions of frost and snow, A'', nivalis 

 and others are partial to the flowers of Cyathodes. In some forests, where a foreign 

 Rubus has become a pest, they visit these flowers in great abundance. The different 

 species of these bees by no means restrict their attention to one kind of plant, but 

 collect from the most diverse kinds. 



The most interesting fact in connection with the Hawaiian Prosopidae is that 

 a small group of five species of Nesoprosopis has become inquilinous or parasitic 

 on their industrial congeners. As is well known, amongst bees in general, parasitism 

 of this kind has arisen independently in various groups. Thus the Megachilidae 

 (sens, lat.) have given rise independently to the Coelioxys group of parasites 

 (Coelioxinae Ashm.) through forms allied to Megachile itself, and to the Stelis group 

 of parasites through forms allied to Anthidiiini (Anthidiinae Ashm.). The Antho- 

 phoridae have given rise to the parasitic Melecta group (Nomadidae partini Ashm.) 

 while the origin of some other parasitic forms is still involved in doubt. The case, 

 hitherto known, in which the least modification has taken place between host and 

 parasite in bees is that of Bonibus and Psithyrus, where the males differ very slightly 

 in structure, although Ashmead has gone so far as to make these genera represent 

 distinct families. In all these cases the main difference between the parasite and 

 the industrial form, from which it has sprung, lies in the disappearance of such 

 structures as are concerned in the gathering of food for the nurture of its young, 

 and therefore the female parasite is chiefly affected in most cases. This is likewise 

 the case in the parasitic Nesoprosopis, the distinctive curved hairs of the front tarsi, 

 whereby the pollen is swept towards the mouth, having undergone obvious modification. 

 I cannot, however, see the slightest character, whereby the males could be separated 

 generically from the industrial forms ; some of them indeed are not too easily separated 

 from the latter specifically. It may be supposed that these Hawaiian species show 

 the earliest stage in modification of industrial bees into parasitic, as at present known. 

 Their parasitic habits are complete, that is, the parasitic forms never store their own cells. 



The cells of N'esoprosopis are translucent and of dry gelatinous appearance, being 

 impervious to the fluid honey stored therein. Such pollen as is mixed in this honey, 

 is regurgitated with it, since the Prosopidae possess no external arrangement for 

 carrying a load, as do most industrial bees. Rapid inward strokes of the front feet, 

 which, as has been said, are provided with special hairs, sweep the pollen grains from 

 the anthers of the flower towards the mouth. 



