378 Mr Perkins, Notes on some Hawaiian Insects. [Dec. 6, 



Like the other orders of Insects the Hymenoptera are repre- 

 sented by a very few types out of the enormous number that exist 

 elsewhere. Thus the bees, excluding a few isolated forms, which 

 have either certainly or probably been introduced by man, are 

 represented by a single genus ; the wasps also by a single genus, 

 and the Fossors by two genera of Crabronidae, and two closely 

 allied forms of Mimesidae. It is to the remarkable evolution of 

 species of each of these types that the comparative wealth of the 

 aculeate hymenoptera is due. Thus while there are a very few 

 genera which can be looked upon as endemic, the average number 

 of species to each genus is very great, this number being about 28. 

 Most numerous of all in species is the genus Odynerus represented 

 in the Islands by some 80 distinct forms. They are one of the most 

 important elements in the fauna, and are sufficiently numerous to 

 attract the attention of people not particularly interested in such 

 things, the more so as one or two of the species abound around 

 houses, and avail themselves of holes in woodwork or furniture 

 for forming their cells. Although intimately related to one 

 another, and extremely similar in general appearance, in realit} 7 

 they exhibit a very great variety of structure. If one collects 

 these wasps over the Islands from Oahu to Hawaii, the general 

 blackness of their colour is very remarkable. Some are more or 

 less marked with red, the markings being rarely noticeable, unless 

 the insect is caught and examined, and a few have one or two 

 narrow bands of a pale yellow colour on the hind-body, which 

 also are not as a rule easily noticed. Many are entirely black. 

 If now one compares with these a collection of the species from 

 the Island of Kauai a difference is at once seen. Excluding one 

 or two species which frequent the coast and, scarcely modified, 

 have a wide distribution over the Islands, all the species have two 

 distinct yellowish abdominal bands, the second being nearly always 

 evidently wider than the first. When the insects are on the 

 wing, these bands are plainly seen. It so happened that in the 

 course of my collecting over the Islands, Kauai was not visited 

 until after the other islands had been collected over, so that it 

 was no small surprise to find the wasps so distinct in superficial 

 appearance. At the time I supposed that the Kauai species would 

 turn out to be very closely related to one another, at least more 

 closely than to those on the windward islands. This however 

 proves not to be the case, for some of the most remotely allied 

 species on the other islands, are represented on Kauai by species 

 which are structurally only slightly modified forms of the same, 

 although their superficial appearance is very distinct. For some 

 reason or other it is clear that the O&yneri of Kauai have assumed 

 an appearance almost unique amongst the great number of species 

 occurring in the Islands — they have what are called ' warning 



